Apparatus for transmitting broadcast signals, apparatus for receiving broadcast signals, method for transmitting broadcast signals and method for receiving broadcast signals

ABSTRACT

A method and an apparatus for transmitting broadcast signals thereof are disclosed. The apparatus for transmitting broadcast signals, the apparatus comprises an encoder to encode service data corresponding to a number of physical paths, a time interleaver to time interleave the encoded service data in each physical path, a frame builder to build at least one signal frame including the time interleaved service data, a modulator to modulate data in the built at least one signal frame by an OFDM (Orthogonal Frequency Division Multiplex) scheme and a transmitter to transmitting the broadcast signals having the modulated data.

This application claims the benefit of U.S. Provisional Application No.62/006,849 and No. 62/006,858 filed on Jun. 2, 2014, which is herebyincorporated by reference as if fully set forth herein.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to an apparatus for transmitting broadcastsignals, an apparatus for receiving broadcast signals and methods fortransmitting and receiving broadcast signals.

Discussion of the Related Art

As analog broadcast signal transmission comes to an end, varioustechnologies for transmitting/receiving digital broadcast signals arebeing developed. A digital broadcast signal may include a larger amountof video/audio data than an analog broadcast signal and further includevarious types of additional data in addition to the video/audio data.

That is, a digital broadcast system can provide HD (high definition)images, multi-channel audio and various additional services. However,data transmission efficiency for transmission of large amounts of data,robustness of transmission/reception networks and network flexibility inconsideration of mobile reception equipment need to be improved fordigital broadcast.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to an apparatus fortransmitting broadcast signals and an apparatus for receiving broadcastsignals for future broadcast services and methods for transmitting andreceiving broadcast signals for future broadcast services.

An object of the present invention is to provide an apparatus and methodfor transmitting broadcast signals to multiplex data of a broadcasttransmission/reception system providing two or more different broadcastservices in a time domain and transmit the multiplexed data through thesame RF signal bandwidth and an apparatus and method for receivingbroadcast signals corresponding thereto.

Another object of the present invention is to provide an apparatus fortransmitting broadcast signals, an apparatus for receiving broadcastsignals and methods for transmitting and receiving broadcast signals toclassify data corresponding to services by components, transmit datacorresponding to each component as a data pipe, receive and process thedata

Still another object of the present invention is to provide an apparatusfor transmitting broadcast signals, an apparatus for receiving broadcastsignals and methods for transmitting and receiving broadcast signals tosignal signaling information necessary to provide broadcast signals.

Technical Solution

To achieve the object and other advantages and in accordance with thepurpose of the invention, as embodied and broadly described herein, amethod for transmitting broadcast signals, the method comprises encodingservice data corresponding to a number of physical paths, timeinterleaving the encoded service data in each physical path, building atleast one signal frame including the time interleaved service data,modulating data in the built at least one signal frame by an OFDM(Orthogonal Frequency Division Multiplex) scheme and transmitting thebroadcast signals having the modulated data.

Advantageous Effects

The present invention can process data according to servicecharacteristics to control QoS (Quality of Services) for each service orservice component, thereby providing various broadcast services.

The present invention can achieve transmission flexibility bytransmitting various broadcast services through the same RF signalbandwidth.

The present invention can improve data transmission efficiency andincrease robustness of transmission/reception of broadcast signals usinga MIMO system.

According to the present invention, it is possible to provide broadcastsignal transmission and reception methods and apparatus capable ofreceiving digital broadcast signals without error even with mobilereception equipment or in an indoor environment.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this application, illustrate embodiment(s) of the invention andtogether with the description serve to explain the principle of theinvention. In the drawings:

FIG. 1 illustrates a structure of an apparatus for transmittingbroadcast signals for future broadcast services according to anembodiment of the present invention.

FIG. 2 illustrates an input formatting block according to one embodimentof the present invention.

FIG. 3 illustrates an input formatting block according to anotherembodiment of the present invention.

FIG. 4 illustrates an input formatting block according to anotherembodiment of the present invention.

FIG. 5 illustrates a BICM block according to an embodiment of thepresent invention.

FIG. 6 illustrates a BICM block according to another embodiment of thepresent invention.

FIG. 7 illustrates a frame building block according to one embodiment ofthe present invention.

FIG. 8 illustrates an OFDM generation block according to an embodimentof the present invention.

FIG. 9 illustrates a structure of an apparatus for receiving broadcastsignals for future broadcast services according to an embodiment of thepresent invention.

FIG. 10 illustrates a frame structure according to an embodiment of thepresent invention.

FIG. 11 illustrates a signaling hierarchy structure of the frameaccording to an embodiment of the present invention.

FIG. 12 illustrates preamble signaling data according to an embodimentof the present invention.

FIG. 13 illustrates PLS1 data according to an embodiment of the presentinvention.

FIG. 14 illustrates PLS2 data according to an embodiment of the presentinvention.

FIG. 15 illustrates PLS2 data according to another embodiment of thepresent invention.

FIG. 16 illustrates a logical structure of a frame according to anembodiment of the present invention.

FIG. 17 illustrates PLS mapping according to an embodiment of thepresent invention.

FIG. 18 illustrates EAC mapping according to an embodiment of thepresent invention.

FIG. 19 illustrates FIC mapping according to an embodiment of thepresent invention.

FIG. 20 illustrates a type of DP according to an embodiment of thepresent invention.

FIG. 21 illustrates DP mapping according to an embodiment of the presentinvention.

FIG. 22 illustrates an FEC structure according to an embodiment of thepresent invention.

FIG. 23 illustrates a bit interleaving according to an embodiment of thepresent invention.

FIG. 24 illustrates a cell-word demultiplexing according to anembodiment of the present invention.

FIG. 25 illustrates a time interleaving according to an embodiment ofthe present invention.

FIG. 26 illustrates the basic operation of a twisted row-column blockinterleaver according to an embodiment of the present invention.

FIG. 27 illustrates an operation of a twisted row-column blockinterleaver according to another embodiment of the present invention.

FIG. 28 illustrates a diagonal-wise reading pattern of a twistedrow-column block interleaver according to an embodiment of the presentinvention.

FIG. 29 illustrates interleaved XFECBLOCKs from each interleaving arrayaccording to an embodiment of the present invention.

FIG. 30 illustrates a time interleaving process according to anembodiment of the present invention.

FIG. 31 illustrates a time interleaving process according to anotherembodiment of the present invention.

FIG. 32 illustrates a process of generating TI output memory indexesaccording to an embodiment of the present invention.

FIG. 33 illustrates a time deinterleaving process according to anembodiment of the present invention.

FIG. 34 illustrates a time deinterleaving process according to anotherembodiment of the present invention.

FIG. 35 illustrates a process of generating TDI output memory indexesaccording to an embodiment of the present invention.

FIG. 36 is a conceptual diagram illustrating a variable data-rate systemaccording to an embodiment of the present invention.

FIG. 37 illustrates a time interleaving process according to anotherembodiment of the present invention.

FIG. 38 illustrates a process of generating TI output memory indexesaccording to another embodiment of the present invention.

FIG. 39 is a flowchart illustrating a TI memory index generation processaccording to an embodiment of the present invention.

FIG. 40 illustrates a time deinterleaving process according to anotherembodiment of the present invention.

FIG. 41 illustrates a time deinterleaving process according to anotherembodiment of the present invention.

FIG. 42 illustrates a writing method according to an embodiment of thepresent invention.

FIG. 43 is a flowchart illustrating a process of generating TDI memoryindexes according to an embodiment of the present invention.

FIG. 44 is a conceptual diagram illustrating a variable data-rate systemaccording to an embodiment of the present invention.

FIG. 45 is a flowchart illustrating a process of generating TDI memoryindexes according to an embodiment of the present invention.

FIG. 46 illustrates the concept of a variable bit-rate system accordingto an embodiment of the present invention.

FIG. 47 illustrates writing and reading operations of block interleavingaccording to an embodiment of the present invention.

FIG. 48 shows equations representing block interleaving according to anembodiment of the present invention.

FIG. 49 illustrates virtual FEC blocks according to an embodiment of thepresent invention.

FIG. 50 shows equations representing reading operation after insertionof virtual FEC blocks according to an embodiment of the presentinvention.

FIG. 51 is a flowchart illustrating a time interleaving processaccording to an embodiment of the present invention.

FIG. 52 shows equations representing a process of determining a shiftvalue and a maximum TI block size according to an embodiment of thepresent invention.

FIG. 53 illustrates writing operation according to an embodiment of thepresent invention.

FIG. 54 illustrates reading operation according to an embodiment of thepresent invention.

FIG. 55 illustrates a result of skip operation in reading operationaccording to an embodiment of the present invention.

FIG. 56 shows a writing process of time deinterleaving according to anembodiment of the present invention.

FIG. 57 illustrates a writing process of time deinterleaving accordingto another embodiment of the present invention.

FIG. 58 shows equations representing reading operation of timedeinterleaving according to another embodiment of the present invention.

FIG. 59 is a flowchart illustrating a time deinterleaving processaccording to an embodiment of the present invention.

FIG. 60 is a block diagram of a time interleaver according to anotherembodiment of the present invention.

FIG. 61 is a view illustrating a twisted block interleaving operation.

FIG. 62 illustrates a convolutional interleaving operation.

FIG. 63 illustrates output frames based on a reading operation of aconvolutional interleaver.

FIG. 64 is a block diagram of a time deinterleaver according to anembodiment of the present invention.

FIG. 65 is a view illustrating memory configurations of a timeinterleaver and a time deinterleaver.

FIG. 66 is a view illustrating a time deinterleaving operation accordingto an embodiment of the present invention.

FIG. 67 is a view illustrating the structure of a time interleaveraccording to an embodiment of the present invention.

FIG. 68 is a view illustrating a reading operation performed afterconvolutional interleaving.

FIG. 69 is a view illustrating the structure of a time deinterleaveraccording to an embodiment of the present invention.

FIG. 70 is a view illustrating a convolutional deinterleaving operationaccording to an embodiment of the present invention.

FIG. 71 is a view illustrating a twisted deinterleaving operationaccording to an embodiment of the present invention.

FIG. 72 is a flowchart illustrating a method for transmitting broadcastsignals according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings. The detailed description, which will be given below withreference to the accompanying drawings, is intended to explain exemplaryembodiments of the present invention, rather than to show the onlyembodiments that can be implemented according to the present invention.The following detailed description includes specific details in order toprovide a thorough understanding of the present invention. However, itwill be apparent to those skilled in the art that the present inventionmay be practiced without such specific details.

Although most terms used in the present invention have been selectedfrom general ones widely used in the art, some terms have beenarbitrarily selected by the applicant and their meanings are explainedin detail in the following description as needed. Thus, the presentinvention should be understood based upon the intended meanings of theterms rather than their simple names or meanings.

The present invention provides apparatuses and methods for transmittingand receiving broadcast signals for future broadcast services. Futurebroadcast services according to an embodiment of the present inventioninclude a terrestrial broadcast service, a mobile broadcast service, aUHDTV service, etc. The present invention may process broadcast signalsfor the future broadcast services through non-MIMO (Multiple InputMultiple Output) or MIMO according to one embodiment. A non-MIMO schemeaccording to an embodiment of the present invention may include a MISO(Multiple Input Single Output) scheme, a SISO (Single Input SingleOutput) scheme, etc.

While MISO or MIMO uses two antennas in the following for convenience ofdescription, the present invention is applicable to systems using two ormore antennas.

The present invention may defines three physical layer (PL)profiles—base, handheld and advanced profiles—each optimized to minimizereceiver complexity while attaining the performance required for aparticular use case. The physical layer (PHY) profiles are subsets ofall configurations that a corresponding receiver should implement.

The three PHY profiles share most of the functional blocks but differslightly in specific blocks and/or parameters. Additional PHY profilescan be defined in the future. For the system evolution, future profilescan also be multiplexed with the existing profiles in a single RFchannel through a future extension frame (FEF). The details of each PHYprofile are described below.

1. Base Profile

The base profile represents a main use case for fixed receiving devicesthat are usually connected to a roof-top antenna. The base profile alsoincludes portable devices that could be transported to a place butbelong to a relatively stationary reception category. Use of the baseprofile could be extended to handheld devices or even vehicular by someimproved implementations, but those use cases are not expected for thebase profile receiver operation.

Target SNR range of reception is from approximately 10 to 20 dB, whichincludes the 15 dB SNR reception capability of the existing broadcastsystem (e.g. ATSC A/53). The receiver complexity and power consumptionis not as critical as in the battery-operated handheld devices, whichwill use the handheld profile. Key system parameters for the baseprofile are listed in below table 1.

TABLE 1 LDPC codeword length 16K, 64K bits Constellation size 4~10 bpcu(bits per channel use) Time de-interleaving memory size ≤2¹⁹ data cellsPilot patterns Pilot pattern for fixed reception FFT size 16K, 32Kpoints

2. Handheld Profile

The handheld profile is designed for use in handheld and vehiculardevices that operate with battery power. The devices can be moving withpedestrian or vehicle speed. The power consumption as well as thereceiver complexity is very important for the implementation of thedevices of the handheld profile. The target SNR range of the handheldprofile is approximately 0 to 10 dB, but can be configured to reachbelow 0 dB when intended for deeper indoor reception.

In addition to low SNR capability, resilience to the Doppler Effectcaused by receiver mobility is the most important performance attributeof the handheld profile. Key system parameters for the handheld profileare listed in the below table 2.

TABLE 2 LDPC codeword length 16K bits Constellation size 2~8 bpcu Timede-interleaving memory size ≤2¹⁸ data cells Pilot patterns Pilotpatterns for mobile and indoor reception FFT size 8K, 16K points

3. Advanced Profile

The advanced profile provides highest channel capacity at the cost ofmore implementation complexity. This profile requires using MIMOtransmission and reception, and UHDTV service is a target use case forwhich this profile is specifically designed. The increased capacity canalso be used to allow an increased number of services in a givenbandwidth, e.g., multiple SDTV or HDTV services.

The target SNR range of the advanced profile is approximately 20 to 30dB. MIMO transmission may initially use existing elliptically-polarizedtransmission equipment, with extension to full-power cross-polarizedtransmission in the future. Key system parameters for the advancedprofile are listed in below table 3.

TABLE 3 LDPC codeword length 16K, 64K bits Constellation size 8~12 bpcuTime de-interleaving memory size ≤2¹⁹ data cells Pilot patterns Pilotpattern for fixed reception FFT size 16K, 32K points

In this case, the base profile can be used as a profile for both theterrestrial broadcast service and the mobile broadcast service. That is,the base profile can be used to define a concept of a profile whichincludes the mobile profile. Also, the advanced profile can be dividedadvanced profile for a base profile with MIMO and advanced profile for ahandheld profile with MIMO. Moreover, the three profiles can be changedaccording to intention of the designer.

The following terms and definitions may apply to the present invention.The following terms and definitions can be changed according to design.

auxiliary stream: sequence of cells carrying data of as yet undefinedmodulation and coding, which may be used for future extensions or asrequired by broadcasters or network operators

base data pipe: data pipe that carries service signaling data

baseband frame (or BBFRAME): set of Kbch bits which form the input toone FEC encoding process (BCH and LDPC encoding)

cell: modulation value that is carried by one carrier of the OFDMtransmission

coded block: LDPC-encoded block of PLS1 data or one of the LDPC-encodedblocks of PLS2 data

data pipe: logical channel in the physical layer that carries servicedata or related metadata, which may carry one or multiple service(s) orservice component(s).

data pipe unit: a basic unit for allocating data cells to a DP in aframe.

data symbol: OFDM symbol in a frame which is not a preamble symbol (theframe signaling symbol and frame edge symbol is included in the datasymbol)

DP_ID: this 8-bit field identifies uniquely a DP within the systemidentified by the SYSTEM_ID

dummy cell: cell carrying a pseudo-random value used to fill theremaining capacity not used for PLS signaling, DPs or auxiliary streams

emergency alert channel: part of a frame that carries EAS informationdata

frame: physical layer time slot that starts with a preamble and endswith a frame edge symbol

frame repetition unit: a set of frames belonging to same or differentphysical layer profile including a FEF, which is repeated eight times ina super-frame

fast information channel: a logical channel in a frame that carries themapping information between a service and the corresponding base DP

FECBLOCK: set of LDPC-encoded bits of a DP data

FFT size: nominal FFT size used for a particular mode, equal to theactive symbol period Ts expressed in cycles of the elementary period T

frame signaling symbol: OFDM symbol with higher pilot density used atthe start of a frame in certain combinations of FFT size, guard intervaland scattered pilot pattern, which carries a part of the PLS data

frame edge symbol: OFDM symbol with higher pilot density used at the endof a frame in certain combinations of FFT size, guard interval andscattered pilot pattern

frame-group: the set of all the frames having the same PHY profile typein a super-frame.

future extension frame: physical layer time slot within the super-framethat could be used for future extension, which starts with a preamble

Futurecast UTB system: proposed physical layer broadcasting system, ofwhich the input is one or more MPEG2-TS or IP or general stream(s) andof which the output is an RF signal

input stream: A stream of data for an ensemble of services delivered tothe end users by the system.

normal data symbol: data symbol excluding the frame signaling symbol andthe frame edge symbol

PHY profile: subset of all configurations that a corresponding receivershould implement

PLS: physical layer signaling data consisting of PLS1 and PLS2

PLS1: a first set of PLS data carried in the FSS symbols having a fixedsize, coding and modulation, which carries basic information about thesystem as well as the parameters needed to decode the PLS2

NOTE: PLS1 data remains constant for the duration of a frame-group.

PLS2: a second set of PLS data transmitted in the FSS symbol, whichcarries more detailed PLS data about the system and the DPs

PLS2 dynamic data: PLS2 data that may dynamically change frame-by-frame

PLS2 static data: PLS2 data that remains static for the duration of aframe-group

preamble signaling data: signaling data carried by the preamble symboland used to identify the basic mode of the system

preamble symbol: fixed-length pilot symbol that carries basic PLS dataand is located in the beginning of a frame

NOTE: The preamble symbol is mainly used for fast initial band scan todetect the system signal, its timing, frequency offset, and FFT-size.

reserved for future use: not defined by the present document but may bedefined in future

super-frame: set of eight frame repetition units

time interleaving block (TI block): set of cells within which timeinterleaving is carried out, corresponding to one use of the timeinterleaver memory

TI group: unit over which dynamic capacity allocation for a particularDP is carried out, made up of an integer, dynamically varying number ofXFECBLOCKs

NOTE: The TI group may be mapped directly to one frame or may be mappedto multiple frames. It may contain one or more TI blocks.

Type 1 DP: DP of a frame where all DPs are mapped into the frame in TDMfashion

Type 2 DP: DP of a frame where all DPs are mapped into the frame in FDMfashion

XFECBLOCK: set of Ncells cells carrying all the bits of one LDPCFECBLOCK

FIG. 1 illustrates a structure of an apparatus for transmittingbroadcast signals for future broadcast services according to anembodiment of the present invention.

The apparatus for transmitting broadcast signals for future broadcastservices according to an embodiment of the present invention can includean input formatting block 1000, a BICM (Bit interleaved coding &modulation) block 1010, a frame building block 1020, an OFDM (OrthogonalFrequency Division Multiplexing) generation block 1030 and a signalinggeneration block 1040. A description will be given of the operation ofeach module of the apparatus for transmitting broadcast signals.

IP stream/packets and MPEG2-TS are the main input formats, other streamtypes are handled as General Streams. In addition to these data inputs,Management Information is input to control the scheduling and allocationof the corresponding bandwidth for each input stream. One or multiple TSstream(s), IP stream(s) and/or General Stream(s) inputs aresimultaneously allowed.

The input formatting block 1000 can demultiplex each input stream intoone or multiple data pipe(s), to each of which an independent coding andmodulation is applied. The data pipe (DP) is the basic unit forrobustness control, thereby affecting quality-of-service (QoS). One ormultiple service(s) or service component(s) can be carried by a singleDP. Details of operations of the input formatting block 1000 will bedescribed later.

The data pipe is a logical channel in the physical layer that carriesservice data or related metadata, which may carry one or multipleservice(s) or service component(s).

Also, the data pipe unit: a basic unit for allocating data cells to a DPin a frame.

In the BICM block 1010, parity data is added for error correction andthe encoded bit streams are mapped to complex-value constellationsymbols. The symbols are interleaved across a specific interleavingdepth that is used for the corresponding DP. For the advanced profile,MIMO encoding is performed in the BICM block 1010 and the additionaldata path is added at the output for MIMO transmission. Details ofoperations of the BICM block 1010 will be described later.

The Frame Building block 1020 can map the data cells of the input DPsinto the OFDM symbols within a frame. After mapping, the frequencyinterleaving is used for frequency-domain diversity, especially tocombat frequency-selective fading channels. Details of operations of theFrame Building block 1020 will be described later.

After inserting a preamble at the beginning of each frame, the OFDMGeneration block 1030 can apply conventional OFDM modulation having acyclic prefix as guard interval. For antenna space diversity, adistributed MISO scheme is applied across the transmitters. In addition,a Peak-to-Average Power Reduction (PAPR) scheme is performed in the timedomain. For flexible network planning, this proposal provides a set ofvarious FFT sizes, guard interval lengths and corresponding pilotpatterns. Details of operations of the OFDM Generation block 1030 willbe described later.

The Signaling Generation block 1040 can create physical layer signalinginformation used for the operation of each functional block. Thissignaling information is also transmitted so that the services ofinterest are properly recovered at the receiver side. Details ofoperations of the Signaling Generation block 1040 will be describedlater.

FIGS. 2, 3 and 4 illustrate the input formatting block 1000 according toembodiments of the present invention. A description will be given ofeach figure.

FIG. 2 illustrates an input formatting block according to one embodimentof the present invention. FIG. 2 shows an input formatting module whenthe input signal is a single input stream.

The input formatting block illustrated in FIG. 2 corresponds to anembodiment of the input formatting block 1000 described with referenceto FIG. 1.

The input to the physical layer may be composed of one or multiple datastreams. Each data stream is carried by one DP. The mode adaptationmodules slice the incoming data stream into data fields of the basebandframe (BBF). The system supports three types of input data streams:MPEG2-TS, Internet protocol (IP) and Generic stream (GS). MPEG2-TS ischaracterized by fixed length (188 byte) packets with the first bytebeing a sync-byte (0x47). An IP stream is composed of variable length IPdatagram packets, as signaled within IP packet headers. The systemsupports both IPv4 and IPv6 for the IP stream. GS may be composed ofvariable length packets or constant length packets, signaled withinencapsulation packet headers.

(a) shows a mode adaptation block 2000 and a stream adaptation 2010 forsignal DP and (b) shows a PLS generation block 2020 and a PLS scrambler2030 for generating and processing PLS data. A description will be givenof the operation of each block.

The Input Stream Splitter splits the input TS, IP, GS streams intomultiple service or service component (audio, video, etc.) streams. Themode adaptation module 2010 is comprised of a CRC Encoder, BB (baseband)Frame Slicer, and BB Frame Header Insertion block.

The CRC Encoder provides three kinds of CRC encoding for error detectionat the user packet (UP) level, i.e., CRC-8, CRC-16, and CRC-32. Thecomputed CRC bytes are appended after the UP. CRC-8 is used for TSstream and CRC-32 for IP stream. If the GS stream doesn't provide theCRC encoding, the proposed CRC encoding should be applied.

BB Frame Slicer maps the input into an internal logical-bit format. Thefirst received bit is defined to be the MSB. The BB Frame Slicerallocates a number of input bits equal to the available data fieldcapacity. To allocate a number of input bits equal to the BBF payload,the UP packet stream is sliced to fit the data field of BBF.

BB Frame Header Insertion block can insert fixed length BBF header of 2bytes is inserted in front of the BB Frame. The BBF header is composedof STUFFI (1 bit), SYNCD (13 bits), and RFU (2 bits). In addition to thefixed 2-Byte BBF header, BBF can have an extension field (1 or 3 bytes)at the end of the 2-byte BBF header.

The stream adaptation 2010 is comprised of stuffing insertion block andBB scrambler.

The stuffing insertion block can insert stuffing field into a payload ofa BB frame. If the input data to the stream adaptation is sufficient tofill a BB-Frame, STUFFI is set to ‘0’ and the BBF has no stuffing field.Otherwise STUFFI is set to ‘1’ and the stuffing field is insertedimmediately after the BBF header. The stuffing field comprises two bytesof the stuffing field header and a variable size of stuffing data.

The BB scrambler scrambles complete BBF for energy dispersal. Thescrambling sequence is synchronous with the BBF. The scrambling sequenceis generated by the feed-back shift register.

The PLS generation block 2020 can generate physical layer signaling(PLS) data. The PLS provides the receiver with a means to accessphysical layer DPs. The PLS data consists of PLS1 data and PLS2 data.

The PLS1 data is a first set of PLS data carried in the FSS symbols inthe frame having a fixed size, coding and modulation, which carriesbasic information about the system as well as the parameters needed todecode the PLS2 data. The PLS1 data provides basic transmissionparameters including parameters required to enable the reception anddecoding of the PLS2 data. Also, the PLS1 data remains constant for theduration of a frame-group.

The PLS2 data is a second set of PLS data transmitted in the FSS symbol,which carries more detailed PLS data about the system and the DPs. ThePLS2 contains parameters that provide sufficient information for thereceiver to decode the desired DP. The PLS2 signaling further consistsof two types of parameters, PLS2 Static data (PLS2-STAT data) and PLS2dynamic data (PLS2-DYN data). The PLS2 Static data is PLS2 data thatremains static for the duration of a frame-group and the PLS2 dynamicdata is PLS2 data that may dynamically change frame-by-frame.

Details of the PLS data will be described later.

The PLS scrambler 2030 can scramble the generated PLS data for energydispersal.

The above-described blocks may be omitted or replaced by blocks havingsimilar or identical functions.

FIG. 3 illustrates an input formatting block according to anotherembodiment of the present invention.

The input formatting block illustrated in FIG. 3 corresponds to anembodiment of the input formatting block 1000 described with referenceto FIG. 1.

FIG. 3 shows a mode adaptation block of the input formatting block whenthe input signal corresponds to multiple input streams.

The mode adaptation block of the input formatting block for processingthe multiple input streams can independently process the multiple inputstreams.

Referring to FIG. 3, the mode adaptation block for respectivelyprocessing the multiple input streams can include an input streamsplitter 3000, an input stream synchronizer 3010, a compensating delayblock 3020, a null packet deletion block 3030, a head compression block3040, a CRC encoder 3050, a BB frame slicer 3060 and a BB headerinsertion block 3070. Description will be given of each block of themode adaptation block.

Operations of the CRC encoder 3050, BB frame slicer 3060 and BB headerinsertion block 3070 correspond to those of the CRC encoder, BB frameslicer and BB header insertion block described with reference to FIG. 2and thus description thereof is omitted.

The input stream splitter 3000 can split the input TS, IP, GS streamsinto multiple service or service component (audio, video, etc.) streams.

The input stream synchronizer 3010 may be referred as ISSY. The ISSY canprovide suitable means to guarantee Constant Bit Rate (CBR) and constantend-to-end transmission delay for any input data format. The ISSY isalways used for the case of multiple DPs carrying TS, and optionallyused for multiple DPs carrying GS streams.

The compensating delay block 3020 can delay the split TS packet streamfollowing the insertion of ISSY information to allow a TS packetrecombining mechanism without requiring additional memory in thereceiver.

The null packet deletion block 3030, is used only for the TS inputstream case. Some TS input streams or split TS streams may have a largenumber of null-packets present in order to accommodate VBR (variablebit-rate) services in a CBR TS stream. In this case, in order to avoidunnecessary transmission overhead, null-packets can be identified andnot transmitted. In the receiver, removed null-packets can bere-inserted in the exact place where they were originally by referenceto a deleted null-packet (DNP) counter that is inserted in thetransmission, thus guaranteeing constant bit-rate and avoiding the needfor time-stamp (PCR) updating.

The head compression block 3040 can provide packet header compression toincrease transmission efficiency for TS or IP input streams. Because thereceiver can have a priori information on certain parts of the header,this known information can be deleted in the transmitter.

For Transport Stream, the receiver has a-priori information about thesync-byte configuration (0x47) and the packet length (188 Byte). If theinput TS stream carries content that has only one PID, i.e., for onlyone service component (video, audio, etc.) or service sub-component (SVCbase layer, SVC enhancement layer, MVC base view or MVC dependentviews), TS packet header compression can be applied (optionally) to theTransport Stream. IP packet header compression is used optionally if theinput steam is an IP stream.

The above-described blocks may be omitted or replaced by blocks havingsimilar or identical functions.

FIG. 4 illustrates an input formatting block according to anotherembodiment of the present invention.

The input formatting block illustrated in FIG. 4 corresponds to anembodiment of the input formatting block 1000 described with referenceto FIG. 1.

FIG. 4 illustrates a stream adaptation block of the input formattingmodule when the input signal corresponds to multiple input streams.

Referring to FIG. 4, the mode adaptation block for respectivelyprocessing the multiple input streams can include a scheduler 4000, an1-Frame delay block 4010, a stuffing insertion block 4020, an in-bandsignaling 4030, a BB Frame scrambler 4040, a PLS generation block 4050and a PLS scrambler 4060. Description will be given of each block of thestream adaptation block.

Operations of the stuffing insertion block 4020, the BB Frame scrambler4040, the PLS generation block 4050 and the PLS scrambler 4060correspond to those of the stuffing insertion block, BB scrambler, PLSgeneration block and the PLS scrambler described with reference to FIG.2 and thus description thereof is omitted.

The scheduler 4000 can determine the overall cell allocation across theentire frame from the amount of FECBLOCKs of each DP. Including theallocation for PLS, EAC and FIC, the scheduler generate the values ofPLS2-DYN data, which is transmitted as in-band signaling or PLS cell inFSS of the frame. Details of FECBLOCK, EAC and FIC will be describedlater.

The 1-Frame delay block 4010 can delay the input data by onetransmission frame such that scheduling information about the next framecan be transmitted through the current frame for in-band signalinginformation to be inserted into the DPs.

The in-band signaling 4030 can insert un-delayed part of the PLS2 datainto a DP of a frame.

The above-described blocks may be omitted or replaced by blocks havingsimilar or identical functions.

FIG. 5 illustrates a BICM block according to an embodiment of thepresent invention.

The BICM block illustrated in FIG. 5 corresponds to an embodiment of theBICM block 1010 described with reference to FIG. 1.

As described above, the apparatus for transmitting broadcast signals forfuture broadcast services according to an embodiment of the presentinvention can provide a terrestrial broadcast service, mobile broadcastservice, UHDTV service, etc.

Since QoS (quality of service) depends on characteristics of a serviceprovided by the apparatus for transmitting broadcast signals for futurebroadcast services according to an embodiment of the present invention,data corresponding to respective services needs to be processed throughdifferent schemes. Accordingly, the a BICM block according to anembodiment of the present invention can independently process DPs inputthereto by independently applying SISO, MISO and MIMO schemes to thedata pipes respectively corresponding to data paths. Consequently, theapparatus for transmitting broadcast signals for future broadcastservices according to an embodiment of the present invention can controlQoS for each service or service component transmitted through each DP.

(a) shows the BICM block shared by the base profile and the handheldprofile and (b) shows the BICM block of the advanced profile.

The BICM block shared by the base profile and the handheld profile andthe BICM block of the advanced profile can include plural processingblocks for processing each DP.

A description will be given of each processing block of the BICM blockfor the base profile and the handheld profile and the BICM block for theadvanced profile.

A processing block 5000 of the BICM block for the base profile and thehandheld profile can include a Data FEC encoder 5010, a bit interleaver5020, a constellation mapper 5030, an SSD (Signal Space Diversity)encoding block 5040 and a time interleaver 5050.

The Data FEC encoder 5010 can perform the FEC encoding on the input BBFto generate FECBLOCK procedure using outer coding (BCH), and innercoding (LDPC). The outer coding (BCH) is optional coding method. Detailsof operations of the Data FEC encoder 5010 will be described later.

The bit interleaver 5020 can interleave outputs of the Data FEC encoder5010 to achieve optimized performance with combination of the LDPC codesand modulation scheme while providing an efficiently implementablestructure. Details of operations of the bit interleaver 5020 will bedescribed later.

The constellation mapper 5030 can modulate each cell word from the bitinterleaver 5020 in the base and the handheld profiles, or cell wordfrom the Cell-word demultiplexer 5010-1 in the advanced profile usingeither QPSK, QAM-16, non-uniform QAM (NUQ-64, NUQ-256, NUQ-1024) ornon-uniform constellation (NUC-16, NUC-64, NUC-256, NUC-1024) to give apower-normalized constellation point, e1. This constellation mapping isapplied only for DPs. Observe that QAM-16 and NUQs are square shaped,while NUCs have arbitrary shape. When each constellation is rotated byany multiple of 90 degrees, the rotated constellation exactly overlapswith its original one. This “rotation-sense” symmetric property makesthe capacities and the average powers of the real and imaginarycomponents equal to each other. Both NUQs and NUCs are definedspecifically for each code rate and the particular one used is signaledby the parameter DP_MOD filed in PLS2 data.

The SSD encoding block 5040 can precode cells in two (2D), three (3D),and four (4D) dimensions to increase the reception robustness underdifficult fading conditions.

The time interleaver 5050 can operates at the DP level. The parametersof time interleaving (TI) may be set differently for each DP. Details ofoperations of the time interleaver 5050 will be described later.

A processing block 5000-1 of the BICM block for the advanced profile caninclude the Data FEC encoder, bit interleaver, constellation mapper, andtime interleaver. However, the processing block 5000-1 is distinguishedfrom the processing block 5000 further includes a cell-worddemultiplexer 5010-1 and a MIMO encoding block 5020-1.

Also, the operations of the Data FEC encoder, bit interleaver,constellation mapper, and time interleaver in the processing block5000-1 correspond to those of the Data FEC encoder 5010, bit interleaver5020, constellation mapper 5030, and time interleaver 5050 described andthus description thereof is omitted.

The cell-word demultiplexer 5010-1 is used for the DP of the advancedprofile to divide the single cell-word stream into dual cell-wordstreams for MIMO processing. Details of operations of the cell-worddemultiplexer 5010-1 will be described later.

The MIMO encoding block 5020-1 can processing the output of thecell-word demultiplexer 5010-1 using MIMO encoding scheme. The MIMOencoding scheme was optimized for broadcasting signal transmission. TheMIMO technology is a promising way to get a capacity increase but itdepends on channel characteristics. Especially for broadcasting, thestrong LOS component of the channel or a difference in the receivedsignal power between two antennas caused by different signal propagationcharacteristics makes it difficult to get capacity gain from MIMO. Theproposed MIMO encoding scheme overcomes this problem using arotation-based pre-coding and phase randomization of one of the MIMOoutput signals.

MIMO encoding is intended for a 2×2 MIMO system requiring at least twoantennas at both the transmitter and the receiver. Two MIMO encodingmodes are defined in this proposal; full-rate spatial multiplexing(FR-SM) and full-rate full-diversity spatial multiplexing (FRFD-SM). TheFR-SM encoding provides capacity increase with relatively smallcomplexity increase at the receiver side while the FRFD-SM encodingprovides capacity increase and additional diversity gain with a greatcomplexity increase at the receiver side. The proposed MIMO encodingscheme has no restriction on the antenna polarity configuration.

MIMO processing is required for the advanced profile frame, which meansall DPs in the advanced profile frame are processed by the MIMO encoder.MIMO processing is applied at DP level. Pairs of the ConstellationMapper outputs NUQ (e1,i and e2,i) are fed to the input of the MIMOEncoder. Paired MIMO Encoder output (g1,i and g2,i) is transmitted bythe same carrier k and OFDM symbol l of their respective TX antennas.

The above-described blocks may be omitted or replaced by blocks havingsimilar or identical functions.

FIG. 6 illustrates a BICM block according to another embodiment of thepresent invention.

The BICM block illustrated in FIG. 6 corresponds to an embodiment of theBICM block 1010 described with reference to FIG. 1.

FIG. 6 illustrates a BICM block for protection of physical layersignaling (PLS), emergency alert channel (EAC) and fast informationchannel (FIC). EAC is a part of a frame that carries EAS informationdata and FIC is a logical channel in a frame that carries the mappinginformation between a service and the corresponding base DP. Details ofthe EAC and FIC will be described later.

Referring to FIG. 6, the BICM block for protection of PLS, EAC and FICcan include a PLS FEC encoder 6000, a bit interleaver 6010 and aconstellation mapper 6020.

Also, the PLS FEC encoder 6000 can include a scrambler, BCHencoding/zero insertion block, LDPC encoding block and LDPC paritypunturing block. Description will be given of each block of the BICMblock.

The PLS FEC encoder 6000 can encode the scrambled PLS1/2 data, EAC andFIC section.

The scrambler can scramble PLS1 data and PLS2 data before BCH encodingand shortened and punctured LDPC encoding.

The BCH encoding/zero insertion block can perform outer encoding on thescrambled PLS 1/2 data using the shortened BCH code for PLS protectionand insert zero bits after the BCH encoding. For PLS1 data only, theoutput bits of the zero insertion may be permutted before LDPC encoding.

The LDPC encoding block can encode the output of the BCH encoding/zeroinsertion block using LDPC code. To generate a complete coded block,Cldpc, parity bits, Pldpc are encoded systematically from eachzero-inserted PLS information block, Ildpc and appended after it.

C _(ldpc)=[I _(ldpc) P _(ldpc)]=[i ₀ ,i ₁ , . . . ,i _(K) _(ldpc) ₋₁ ,p₀ ,p ₁ , . . . ,p _(N) _(ldpc) _(-K) _(ldpc) ₋₁]  [Math FIG. 1]

The LDPC code parameters for PLS1 and PLS2 are as following table 4.

TABLE 4 Signaling K_(ldpc) code Type K_(sig) K_(bch) N_(bch) _(—)_(parity) (=N_(bch)) N_(ldpc) N_(ldpc) _(—) _(parity) rate Q_(ldpc) PLS1342 1020 60 1080 4320 3240 1/4  36 PLS2 <1021 >1020 2100 2160 7200 50403/10 56

The LDPC parity punturing block can perform puncturing on the PLS1 dataand PLS2 data.

When shortening is applied to the PLS1 data protection, some LDPC paritybits are punctured after LDPC encoding. Also, for the PLS2 dataprotection, the LDPC parity bits of PLS2 are punctured after LDPCencoding. These punctured bits are not transmitted.

The bit interleaver 6010 can interleave the each shortened and puncturedPLS1 data and PLS2 data.

The constellation mapper 6020 can map the bit interleaved PLS1 data andPLS2 data onto constellations.

The above-described blocks may be omitted or replaced by blocks havingsimilar or identical functions.

FIG. 7 illustrates a frame building block according to one embodiment ofthe present invention.

The frame building block illustrated in FIG. 7 corresponds to anembodiment of the frame building block 1020 described with reference toFIG. 1.

Referring to FIG. 7, the frame building block can include a delaycompensation block 7000, a cell mapper 7010 and a frequency interleaver7020. Description will be given of each block of the frame buildingblock.

The delay compensation block 7000 can adjust the timing between the datapipes and the corresponding PLS data to ensure that they are co-timed atthe transmitter end. The PLS data is delayed by the same amount as datapipes are by addressing the delays of data pipes caused by the InputFormatting block and BICM block. The delay of the BICM block is mainlydue to the time interleaver 5050. In-band signaling data carriesinformation of the next TI group so that they are carried one frameahead of the DPs to be signaled. The Delay Compensating block delaysin-band signaling data accordingly.

The cell mapper 7010 can map PLS, EAC, FIC, DPs, auxiliary streams anddummy cells into the active carriers of the OFDM symbols in the frame.The basic function of the cell mapper 7010 is to map data cells producedby the TIs for each of the DPs, PLS cells, and EAC/FIC cells, if any,into arrays of active OFDM cells corresponding to each of the OFDMsymbols within a frame. Service signaling data (such as PSI (programspecific information)/SI) can be separately gathered and sent by a datapipe. The Cell Mapper operates according to the dynamic informationproduced by the scheduler and the configuration of the frame structure.Details of the frame will be described later.

The frequency interleaver 7020 can randomly interleave data cellsreceived from the cell mapper 7010 to provide frequency diversity. Also,the frequency interleaver 7020 can operate on very OFDM symbol paircomprised of two sequential OFDM symbols using a differentinterleaving-seed order to get maximum interleaving gain in a singleframe.

The above-described blocks may be omitted or replaced by blocks havingsimilar or identical functions.

FIG. 8 illustrates an OFDM generation block according to an embodimentof the present invention.

The OFDM generation block illustrated in FIG. 8 corresponds to anembodiment of the OFDM generation block 1030 described with reference toFIG. 1.

The OFDM generation block modulates the OFDM carriers by the cellsproduced by the Frame Building block, inserts the pilots, and producesthe time domain signal for transmission. Also, this block subsequentlyinserts guard intervals, and applies PAPR (Peak-to-Average Power Radio)reduction processing to produce the final RF signal.

Referring to FIG. 8, the OFDM generation block can include a pilot andreserved tone insertion block 8000, a 2D-eSFN encoding block 8010, anIFFT (Inverse Fast Fourier Transform) block 8020, a PAPR reduction block8030, a guard interval insertion block 8040, a preamble insertion block8050, other system insertion block 8060 and a DAC block 8070.Description will be given of each block of the frame building block.

The pilot and reserved tone insertion block 8000 can insert pilots andthe reserved tone.

Various cells within the OFDM symbol are modulated with referenceinformation, known as pilots, which have transmitted values known apriori in the receiver. The information of pilot cells is made up ofscattered pilots, continual pilots, edge pilots, FSS (frame signalingsymbol) pilots and FES (frame edge symbol) pilots. Each pilot istransmitted at a particular boosted power level according to pilot typeand pilot pattern. The value of the pilot information is derived from areference sequence, which is a series of values, one for eachtransmitted carrier on any given symbol. The pilots can be used forframe synchronization, frequency synchronization, time synchronization,channel estimation, and transmission mode identification, and also canbe used to follow the phase noise.

Reference information, taken from the reference sequence, is transmittedin scattered pilot cells in every symbol except the preamble, FSS andFES of the frame. Continual pilots are inserted in every symbol of theframe. The number and location of continual pilots depends on both theFFT size and the scattered pilot pattern. The edge carriers are edgepilots in every symbol except for the preamble symbol. They are insertedin order to allow frequency interpolation up to the edge of thespectrum. FSS pilots are inserted in FSS(s) and FES pilots are insertedin FES. They are inserted in order to allow time interpolation up to theedge of the frame.

The system according to an embodiment of the present invention supportsthe SFN network, where distributed MISO scheme is optionally used tosupport very robust transmission mode. The 2D-eSFN is a distributed MISOscheme that uses multiple TX antennas, each of which is located in thedifferent transmitter site in the SFN network.

The 2D-eSFN encoding block 8010 can process a 2D-eSFN processing todistorts the phase of the signals transmitted from multipletransmitters, in order to create both time and frequency diversity inthe SFN configuration. Hence, burst errors due to low flat fading ordeep-fading for a long time can be mitigated.

The IFFT block 8020 can modulate the output from the 2D-eSFN encodingblock 8010 using OFDM modulation scheme. Any cell in the data symbolswhich has not been designated as a pilot (or as a reserved tone) carriesone of the data cells from the frequency interleaver. The cells aremapped to OFDM carriers.

The PAPR reduction block 8030 can perform a PAPR reduction on inputsignal using various PAPR reduction algorithm in the time domain.

The guard interval insertion block 8040 can insert guard intervals andthe preamble insertion block 8050 can insert preamble in front of thesignal. Details of a structure of the preamble will be described later.The other system insertion block 8060 can multiplex signals of aplurality of broadcast transmission/reception systems in the time domainsuch that data of two or more different broadcast transmission/receptionsystems providing broadcast services can be simultaneously transmittedin the same RF signal bandwidth. In this case, the two or more differentbroadcast transmission/reception systems refer to systems providingdifferent broadcast services. The different broadcast services may referto a terrestrial broadcast service, mobile broadcast service, etc. Datarelated to respective broadcast services can be transmitted throughdifferent frames.

The DAC block 8070 can convert an input digital signal into an analogsignal and output the analog signal. The signal output from the DACblock 7800 can be transmitted through multiple output antennas accordingto the physical layer profiles. A Tx antenna according to an embodimentof the present invention can have vertical or horizontal polarity.

The above-described blocks may be omitted or replaced by blocks havingsimilar or identical functions according to design.

FIG. 9 illustrates a structure of an apparatus for receiving broadcastsignals for future broadcast services according to an embodiment of thepresent invention.

The apparatus for receiving broadcast signals for future broadcastservices according to an embodiment of the present invention cancorrespond to the apparatus for transmitting broadcast signals forfuture broadcast services, described with reference to FIG. 1.

The apparatus for receiving broadcast signals for future broadcastservices according to an embodiment of the present invention can includea synchronization & demodulation module 9000, a frame parsing module9010, a demapping & decoding module 9020, an output processor 9030 and asignaling decoding module 9040. A description will be given of operationof each module of the apparatus for receiving broadcast signals.

The synchronization & demodulation module 9000 can receive input signalsthrough m Rx antennas, perform signal detection and synchronization withrespect to a system corresponding to the apparatus for receivingbroadcast signals and carry out demodulation corresponding to a reverseprocedure of the procedure performed by the apparatus for transmittingbroadcast signals.

The frame parsing module 9010 can parse input signal frames and extractdata through which a service selected by a user is transmitted. If theapparatus for transmitting broadcast signals performs interleaving, theframe parsing module 9010 can carry out deinterleaving corresponding toa reverse procedure of interleaving. In this case, the positions of asignal and data that need to be extracted can be obtained by decodingdata output from the signaling decoding module 9040 to restorescheduling information generated by the apparatus for transmittingbroadcast signals.

The demapping & decoding module 9020 can convert the input signals intobit domain data and then deinterleave the same as necessary. Thedemapping & decoding module 9020 can perform demapping for mappingapplied for transmission efficiency and correct an error generated on atransmission channel through decoding. In this case, the demapping &decoding module 9020 can obtain transmission parameters necessary fordemapping and decoding by decoding the data output from the signalingdecoding module 9040.

The output processor 9030 can perform reverse procedures of variouscompression/signal processing procedures which are applied by theapparatus for transmitting broadcast signals to improve transmissionefficiency. In this case, the output processor 9030 can acquirenecessary control information from data output from the signalingdecoding module 9040. The output of the output processor 8300corresponds to a signal input to the apparatus for transmittingbroadcast signals and may be MPEG-TSs, IP streams (v4 or v6) and genericstreams.

The signaling decoding module 9040 can obtain PLS information from thesignal demodulated by the synchronization & demodulation module 9000. Asdescribed above, the frame parsing module 9010, demapping & decodingmodule 9020 and output processor 9030 can execute functions thereofusing the data output from the signaling decoding module 9040.

FIG. 10 illustrates a frame structure according to an embodiment of thepresent invention.

FIG. 10 shows an example configuration of the frame types and FRUs in asuper-frame. (a) shows a super frame according to an embodiment of thepresent invention, (b) shows FRU (Frame Repetition Unit) according to anembodiment of the present invention, (c) shows frames of variable PHYprofiles in the FRU and (d) shows a structure of a frame.

A super-frame may be composed of eight FRUs. The FRU is a basicmultiplexing unit for TDM of the frames, and is repeated eight times ina super-frame.

Each frame in the FRU belongs to one of the PHY profiles, (base,handheld, advanced) or FEF. The maximum allowed number of the frames inthe FRU is four and a given PHY profile can appear any number of timesfrom zero times to four times in the FRU (e.g., base, base, handheld,advanced). PHY profile definitions can be extended using reserved valuesof the PHY_PROFILE in the preamble, if required.

The FEF part is inserted at the end of the FRU, if included. When theFEF is included in the FRU, the minimum number of FEFs is 8 in asuper-frame. It is not recommended that FEF parts be adjacent to eachother.

One frame is further divided into a number of OFDM symbols and apreamble. As shown in (d), the frame comprises a preamble, one or moreframe signaling symbols (FSS), normal data symbols and a frame edgesymbol (FES).

The preamble is a special symbol that enables fast Futurecast UTB systemsignal detection and provides a set of basic transmission parameters forefficient transmission and reception of the signal. The detaileddescription of the preamble will be will be described later.

The main purpose of the FSS(s) is to carry the PLS data. For fastsynchronization and channel estimation, and hence fast decoding of PLSdata, the FSS has more dense pilot pattern than the normal data symbol.The FES has exactly the same pilots as the FSS, which enablesfrequency-only interpolation within the FES and temporal interpolation,without extrapolation, for symbols immediately preceding the FES.

FIG. 11 illustrates a signaling hierarchy structure of the frameaccording to an embodiment of the present invention.

FIG. 11 illustrates the signaling hierarchy structure, which is splitinto three main parts: the preamble signaling data 11000, the PLS1 data11010 and the PLS2 data 11020. The purpose of the preamble, which iscarried by the preamble symbol in every frame, is to indicate thetransmission type and basic transmission parameters of that frame. ThePLS1 enables the receiver to access and decode the PLS2 data, whichcontains the parameters to access the DP of interest. The PLS2 iscarried in every frame and split into two main parts: PLS2-STAT data andPLS2-DYN data. The static and dynamic portion of PLS2 data is followedby padding, if necessary.

FIG. 12 illustrates preamble signaling data according to an embodimentof the present invention.

Preamble signaling data carries 21 bits of information that are neededto enable the receiver to access PLS data and trace DPs within the framestructure. Details of the preamble signaling data are as follows:

PHY_PROFILE: This 3-bit field indicates the PHY profile type of thecurrent frame. The mapping of different PHY profile types is given inbelow table 5.

TABLE 5 Value PHY profile 000 Base profile 001 Handheld profile 010Advanced profiled 011~110 Reserved 111 FEF

FFT_SIZE: This 2 bit field indicates the FFT size of the current framewithin a frame-group, as described in below table 6.

TABLE 6 Value FFT size 00 8K FFT 01 16K FFT 10 32K FFT 11 Reserved

GI_FRACTION: This 3 bit field indicates the guard interval fractionvalue in the current super-frame, as described in below table 7.

TABLE 7 Value GI_FRACTION 000 ⅕ 001 1/10 010 1/20 011 1/40 100 1/80 1011/160 110~111 Reserved

EAC_FLAG: This 1 bit field indicates whether the EAC is provided in thecurrent frame. If this field is set to ‘1’, emergency alert service(EAS) is provided in the current frame. If this field set to ‘0’, EAS isnot carried in the current frame. This field can be switched dynamicallywithin a super-frame.

PILOT_MODE: This 1-bit field indicates whether the pilot mode is mobilemode or fixed mode for the current frame in the current frame-group. Ifthis field is set to ‘0’, mobile pilot mode is used. If the field is setto ‘1’, the fixed pilot mode is used.

PAPR_FLAG: This 1-bit field indicates whether PAPR reduction is used forthe current frame in the current frame-group. If this field is set tovalue ‘1’, tone reservation is used for PAPR reduction. If this field isset to ‘0’, PAPR reduction is not used.

FRU_CONFIGURE: This 3-bit field indicates the PHY profile typeconfigurations of the frame repetition units (FRU) that are present inthe current super-frame. All profile types conveyed in the currentsuper-frame are identified in this field in all preambles in the currentsuper-frame. The 3-bit field has a different definition for eachprofile, as show in below table 8.

TABLE 8 Current Current Current PHY_PROFILE = PHY_PROFILE = CurrentPHY_PROFILE = ‘001’ ‘010’ PHY_PROFILE = ‘000’ (base) (handheld)(advanced) ‘111’ (FEF) FRU_CONFIGURE = Only base Only handheld Onlyadvanced Only FEF 000 profile profile present profile present presentpresent FRU_CONFIGURE = Handheld Base profile Base profile Base profile1XX profile present present present present FRU_CONFIGURE = AdvancedAdvanced Handheld Handheld X1X profile profile profile profile presentpresent present present FRU_CONFIGURE = FEF FEF FEF Advanced XX1 presentpresent present profile present

RESERVED: This 7-bit field is reserved for future use.

FIG. 13 illustrates PLS1 data according to an embodiment of the presentinvention.

PLS1 data provides basic transmission parameters including parametersrequired to enable the reception and decoding of the PLS2. As abovementioned, the PLS1 data remain unchanged for the entire duration of oneframe-group. The detailed definition of the signaling fields of the PLS1data are as follows:

PREAMBLE_DATA: This 20-bit field is a copy of the preamble signalingdata excluding the EAC_FLAG.

NUM_FRAME_FRU: This 2-bit field indicates the number of the frames perFRU.

PAYLOAD_TYPE: This 3-bit field indicates the format of the payload datacarried in the frame-group. PAYLOAD_TYPE is signaled as shown in table9.

TABLE 9 value Payload type 1XX TS stream is transmitted X1X IP stream istransmitted XX1 GS stream is transmitted

NUM_FSS: This 2-bit field indicates the number of FSS symbols in thecurrent frame.

SYSTEM_VERSION: This 8-bit field indicates the version of thetransmitted signal format. The SYSTEM_VERSION is divided into two 4-bitfields, which are a major version and a minor version.

Major version: The MSB four bits of SYSTEM_VERSION field indicate majorversion information. A change in the major version field indicates anon-backward-compatible change. The default value is ‘0000’. For theversion described in this standard, the value is set to ‘0000’.

Minor version: The LSB four bits of SYSTEM_VERSION field indicate minorversion information. A change in the minor version field isbackward-compatible.

CELL_ID: This is a 16-bit field which uniquely identifies a geographiccell in an ATSC network. An ATSC cell coverage area may consist of oneor more frequencies, depending on the number of frequencies used perFuturecast UTB system. If the value of the CELL_ID is not known orunspecified, this field is set to ‘0’.

NETWORK_ID: This is a 16-bit field which uniquely identifies the currentATSC network.

SYSTEM_ID: This 16-bit field uniquely identifies the Futurecast UTBsystem within the ATSC network. The Futurecast UTB system is theterrestrial broadcast system whose input is one or more input streams(TS, IP, GS) and whose output is an RF signal. The Futurecast UTB systemcarries one or more PHY profiles and FEF, if any. The same FuturecastUTB system may carry different input streams and use different RFfrequencies in different geographical areas, allowing local serviceinsertion. The frame structure and scheduling is controlled in one placeand is identical for all transmissions within a Futurecast UTB system.One or more Futurecast UTB systems may have the same SYSTEM_ID meaningthat they all have the same physical layer structure and configuration.

The following loop consists of FRU_PHY_PROFILE, FRU_FRAME_LENGTH,FRU_GI_FRACTION, and RESERVED which are used to indicate the FRUconfiguration and the length of each frame type. The loop size is fixedso that four PHY profiles (including a FEF) are signaled within the FRU.If NUM_FRAME_FRU is less than 4, the unused fields are filled withzeros.

FRU_PHY_PROFILE: This 3-bit field indicates the PHY profile type of the(i+1)th (i is the loop index) frame of the associated FRU. This fielduses the same signaling format as shown in the table 8.

FRU_FRAME_LENGTH: This 2-bit field indicates the length of the (i+1)thframe of the associated FRU. Using FRU_FRAME_LENGTH together withFRU_GI_FRACTION, the exact value of the frame duration can be obtained.

FRU_GI_FRACTION: This 3-bit field indicates the guard interval fractionvalue of the (i+1)th frame of the associated FRU. FRU_GI_FRACTION issignaled according to the table 7.

RESERVED: This 4-bit field is reserved for future use.

The following fields provide parameters for decoding the PLS2 data.

PLS2_FEC_TYPE: This 2-bit field indicates the FEC type used by the PLS2protection. The FEC type is signaled according to table 10. The detailsof the LDPC codes will be described later.

TABLE 10 Content PLS2 FEC type 00 4K-1/4 and 7K-3/10 LDPC codes 01~11Reserved

PLS2_MOD: This 3-bit field indicates the modulation type used by thePLS2. The modulation type is signaled according to table 11.

TABLE 11 Value PLS2_MODE 000 BPSK 001 QPSK 010 QAM-16 011 NUQ-64 100~111Reserved

PLS2_SIZE_CELL: This 15-bit field indicates Ctotal_partial_block, thesize (specified as the number of QAM cells) of the collection of fullcoded blocks for PLS2 that is carried in the current frame-group. Thisvalue is constant during the entire duration of the current frame-group.

PLS2_STAT_SIZE_BIT: This 14-bit field indicates the size, in bits, ofthe PLS2-STAT for the current frame-group. This value is constant duringthe entire duration of the current frame-group.

PLS2_DYN_SIZE_BIT: This 14-bit field indicates the size, in bits, of thePLS2-DYN for the current frame-group. This value is constant during theentire duration of the current frame-group.

PLS2_REP_FLAG: This 1-bit flag indicates whether the PLS2 repetitionmode is used in the current frame-group. When this field is set to value‘1’, the PLS2 repetition mode is activated. When this field is set tovalue ‘0’, the PLS2 repetition mode is deactivated.

PLS2_REP_SIZE_CELL: This 15-bit field indicates Ctotal_partial_block,the size (specified as the number of QAM cells) of the collection ofpartial coded blocks for PLS2 carried in every frame of the currentframe-group, when PLS2 repetition is used. If repetition is not used,the value of this field is equal to 0. This value is constant during theentire duration of the current frame-group.

PLS2_NEXT_FEC_TYPE: This 2-bit field indicates the FEC type used forPLS2 that is carried in every frame of the next frame-group. The FECtype is signaled according to the table 10.

PLS2_NEXT_MOD: This 3-bit field indicates the modulation type used forPLS2 that is carried in every frame of the next frame-group. Themodulation type is signaled according to the table 11.

PLS2_NEXT_REP_FLAG: This 1-bit flag indicates whether the PLS2repetition mode is used in the next frame-group. When this field is setto value ‘1’, the PLS2 repetition mode is activated. When this field isset to value ‘0’, the PLS2 repetition mode is deactivated.

PLS2_NEXT_REP_SIZE_CELL: This 15-bit field indicates Ctotal_full_block,The size (specified as the number of QAM cells) of the collection offull coded blocks for PLS2 that is carried in every frame of the nextframe-group, when PLS2 repetition is used. If repetition is not used inthe next frame-group, the value of this field is equal to 0. This valueis constant during the entire duration of the current frame-group.

PLS2_NEXT_REP_STAT_SIZE_BIT: This 14-bit field indicates the size, inbits, of the PLS2-STAT for the next frame-group. This value is constantin the current frame-group.

PLS2_NEXT_REP_DYN_SIZE_BIT: This 14-bit field indicates the size, inbits, of the PLS2-DYN for the next frame-group. This value is constantin the current frame-group.

PLS2_AP_MODE: This 2-bit field indicates whether additional parity isprovided for PLS2 in the current frame-group. This value is constantduring the entire duration of the current frame-group. The below table12 gives the values of this field. When this field is set to ‘00’,additional parity is not used for the PLS2 in the current frame-group.

TABLE 12 Value PLS2-AP mode 00 AP is not provided 01 AP1 mode 10~11Reserved

PLS2_AP_SIZE_CELL: This 15-bit field indicates the size (specified asthe number of QAM cells) of the additional parity bits of the PLS2. Thisvalue is constant during the entire duration of the current frame-group.

PLS2_NEXT_AP_MODE: This 2-bit field indicates whether additional parityis provided for PLS2 signaling in every frame of next frame-group. Thisvalue is constant during the entire duration of the current frame-group.The table 12 defines the values of this field

PLS2_NEXT_AP_SIZE_CELL: This 15-bit field indicates the size (specifiedas the number of QAM cells) of the additional parity bits of the PLS2 inevery frame of the next frame-group. This value is constant during theentire duration of the current frame-group.

RESERVED: This 32-bit field is reserved for future use.

CRC_32: A 32-bit error detection code, which is applied to the entirePLS1 signaling.

FIG. 14 illustrates PLS2 data according to an embodiment of the presentinvention.

FIG. 14 illustrates PLS2-STAT data of the PLS2 data. The PLS2-STAT dataare the same within a frame-group, while the PLS2-DYN data provideinformation that is specific for the current frame.

The details of fields of the PLS2-STAT data are as follows:

FIC_FLAG: This 1-bit field indicates whether the FIC is used in thecurrent frame-group. If this field is set to ‘1’, the FIC is provided inthe current frame. If this field set to ‘0’, the FIC is not carried inthe current frame. This value is constant during the entire duration ofthe current frame-group.

AUX_FLAG: This 1-bit field indicates whether the auxiliary stream(s) isused in the current frame-group. If this field is set to ‘1’, theauxiliary stream is provided in the current frame. If this field set to‘0’, the auxiliary stream is not carried in the current frame. Thisvalue is constant during the entire duration of current frame-group.

NUM_DP: This 6-bit field indicates the number of DPs carried within thecurrent frame. The value of this field ranges from 1 to 64, and thenumber of DPs is NUM_DP+1.

DP_ID: This 6-bit field identifies uniquely a DP within a PHY profile.

DP_TYPE: This 3-bit field indicates the type of the DP. This is signaledaccording to the below table 13.

TABLE 13 Value DP Type 000 DP Type 1 001 DP Type 2 010~111 reserved

DP_GROUP_ID: This 8-bit field identifies the DP group with which thecurrent DP is associated. This can be used by a receiver to access theDPs of the service components associated with a particular service,which will have the same DP_GROUP_ID.

BASE_DP_ID: This 6-bit field indicates the DP carrying service signalingdata (such as PSI/SI) used in the Management layer. The DP indicated byBASE_DP_ID may be either a normal DP carrying the service signaling dataalong with the service data or a dedicated DP carrying only the servicesignaling data

DP_FEC_TYPE: This 2-bit field indicates the FEC type used by theassociated DP. The FEC type is signaled according to the below table 14.

TABLE 14 Value FEC_TYPE 00 16K LDPC 01 64K LDPC 10~11 Reserved

DP_COD: This 4-bit field indicates the code rate used by the associatedDP. The code rate is signaled according to the below table 15.

TABLE 15 Value Code rate 0000 5/15 0001 6/15 0010 7/15 0011 8/15 01009/15 0101 10/15 0110 11/15 0111 12/15 1000 13/15 1001~1111 Reserved

DP_MOD: This 4-bit field indicates the modulation used by the associatedDP. The modulation is signaled according to the below table 16.

TABLE 16 Value Modulation 0000 QPSK 0001 QAM-16 0010 NUQ-64 0011 NUQ-2560100 NUQ-1024 0101 NUC-16 0110 NUC-64 0111 NUC-256 1000 NUC-10241001~1111 reserved

DP_SSD_FLAG: This 1-bit field indicates whether the SSD mode is used inthe associated DP. If this field is set to value ‘1’, SSD is used. Ifthis field is set to value ‘0’, SSD is not used.

The following field appears only if PHY_PROFILE is equal to ‘010’, whichindicates the advanced profile:

DP_MIMO: This 3-bit field indicates which type of MIMO encoding processis applied to the associated DP. The type of MIMO encoding process issignaled according to the table 17.

TABLE 17 Value MIMO encoding 000 FR-SM 001 FRFD-SM 010~111 reserved

DP_TI_TYPE: This 1-bit field indicates the type of time-interleaving. Avalue of ‘0’ indicates that one TI group corresponds to one frame andcontains one or more TI-blocks. A value of ‘1’ indicates that one TIgroup is carried in more than one frame and contains only one TI-block.

DP_TI_LENGTH: The use of this 2-bit field (the allowed values are only1, 2, 4, 8) is determined by the values set within the DP_TI_TYPE fieldas follows:

If the DP_TI_TYPE is set to the value ‘1’, this field indicates PI, thenumber of the frames to which each TI group is mapped, and there is oneTI-block per TI group (NTI=1). The allowed PI values with 2-bit fieldare defined in the below table 18.

If the DP_TI_TYPE is set to the value ‘0’, this field indicates thenumber of TI-blocks NTI per TI group, and there is one TI group perframe (PI=1). The allowed PI values with 2-bit field are defined in thebelow table 18.

TABLE 18 2-bit field P_(I) N_(TI) 00 1 1 01 2 2 10 4 3 11 8 4

DP_FRAME_INTERVAL: This 2-bit field indicates the frame interval (IJUMP)within the frame-group for the associated DP and the allowed values are1, 2, 4, 8 (the corresponding 2-bit field is ‘00’, ‘01’, ‘10’, or ‘11’,respectively). For DPs that do not appear every frame of theframe-group, the value of this field is equal to the interval betweensuccessive frames. For example, if a DP appears on the frames 1, 5, 9,13, etc., this field is set to ‘4’. For DPs that appear in every frame,this field is set to ‘1’.

DP_TI_BYPASS: This 1-bit field determines the availability of timeinterleaver 5050. If time interleaving is not used for a DP, it is setto ‘1’. Whereas if time interleaving is used it is set to ‘0’.

DP_FIRST_FRAME_IDX: This 5-bit field indicates the index of the firstframe of the super-frame in which the current DP occurs. The value ofDP_FIRST_FRAME_IDX ranges from 0 to 31

DP_NUM_BLOCK_MAX: This 10-bit field indicates the maximum value ofDP_NUM_BLOCKS for this DP. The value of this field has the same range asDP_NUM_BLOCKS.

DP_PAYLOAD_TYPE: This 2-bit field indicates the type of the payload datacarried by the given DP. DP_PAYLOAD_TYPE is signaled according to thebelow table 19.

TABLE 19 Value Payload Type 00 TS. 01 IP 10 GS 11 reserved

DP_INBAND_MODE: This 2-bit field indicates whether the current DPcarries in-band signaling information. The in-band signaling type issignaled according to the below table 20.

TABLE 20 Value In-band mode 00 In-band signaling is not carried. 01INBAND-PLS is carried only 10 INBAND-ISSY is carried only 11 INBAND-PLSand INBAND-ISSY are carried

DP_PROTOCOL_TYPE: This 2-bit field indicates the protocol type of thepayload carried by the given DP. It is signaled according to the belowtable 21 when input payload types are selected.

TABLE 21 If DP_PAYLOAD_ If DP_PAYLOAD_ If DP_PAYLOAD_ Value TYPE Is TSTYPE Is IP TYPE Is GS 00 MPEG2-TS IPv4 (Note) 01 Reserved IPv6 Reserved10 Reserved Reserved Reserved 11 Reserved Reserved Reserved

DP_CRC_MODE: This 2-bit field indicates whether CRC encoding is used inthe Input Formatting block. The CRC mode is signaled according to thebelow table 22.

TABLE 22 Value CRC mode 00 Not used 01 CRC-8 10 CRC-16 11 CRC-32

DNP_MODE: This 2-bit field indicates the null-packet deletion mode usedby the associated DP when DP_PAYLOAD_TYPE is set to TS (‘00’). DNP_MODEis signaled according to the below table 23. If DP_PAYLOAD_TYPE is notTS (‘00’), DNP_MODE is set to the value ‘00’.

TABLE 23 Value Null-packet deletion mode 00 Not used 01 DNP-NORMAL 10DNP-OFFSET 11 reserved

ISSY_MODE: This 2-bit field indicates the ISSY mode used by theassociated DP when DP_PAYLOAD_TYPE is set to TS (‘00’). The ISSY_MODE issignaled according to the below table 24 If DP_PAYLOAD_TYPE is not TS(‘00’), ISSY_MODE is set to the value ‘00’.

TABLE 24 Value ISSY mode 00 Not used 01 ISSY-UP 10 ISSY-BBF 11 reserved

HC_MODE_TS: This 2-bit field indicates the TS header compression modeused by the associated DP when DP_PAYLOAD_TYPE is set to TS (‘00’). TheHC_MODE_TS is signaled according to the below table 25.

TABLE 25 Value Header compression mode 00 HC_MODE_TS 1 01 HC_MODE_TS 210 HC_MODE_TS 3 11 HC_MODE_TS 4

HC_MODE_IP: This 2-bit field indicates the IP header compression modewhen DP_PAYLOAD_TYPE is set to IP (‘01’). The HC_MODE_IP is signaledaccording to the below table 26.

TABLE 26 Value Header compression mode 00 No compression 01 HC_MODE_IP 110~11 reserved

PID: This 13-bit field indicates the PID number for TS headercompression when DP_PAYLOAD_TYPE is set to TS (‘00’) and HC_MODE_TS isset to ‘01’ or ‘10’.

RESERVED: This 8-bit field is reserved for future use.

The following field appears only if FIC_FLAG is equal to ‘1’:

FIC_VERSION: This 8-bit field indicates the version number of the FIC.

FIC_LENGTH_BYTE: This 13-bit field indicates the length, in bytes, ofthe FIC.

RESERVED: This 8-bit field is reserved for future use.

The following field appears only if AUX_FLAG is equal to ‘1’:

NUM_AUX: This 4-bit field indicates the number of auxiliary streams.Zero means no auxiliary streams are used.

AUX_CONFIG_RFU: This 8-bit field is reserved for future use.

AUX_STREAM_TYPE: This 4-bit is reserved for future use for indicatingthe type of the current auxiliary stream.

AUX_PRIVATE_CONFIG: This 28-bit field is reserved for future use forsignaling auxiliary streams.

FIG. 15 illustrates PLS2 data according to another embodiment of thepresent invention.

FIG. 15 illustrates PLS2-DYN data of the PLS2 data. The values of thePLS2-DYN data may change during the duration of one frame-group, whilethe size of fields remains constant.

The details of fields of the PLS2-DYN data are as follows:

FRAME_INDEX: This 5-bit field indicates the frame index of the currentframe within the super-frame. The index of the first frame of thesuper-frame is set to ‘0’.

PLS_CHANGE_COUNTER: This 4-bit field indicates the number ofsuper-frames ahead where the configuration will change. The nextsuper-frame with changes in the configuration is indicated by the valuesignaled within this field. If this field is set to the value ‘0000’, itmeans that no scheduled change is foreseen: e.g., value ‘1’ indicatesthat there is a change in the next super-frame.

FIC_CHANGE_COUNTER: This 4-bit field indicates the number ofsuper-frames ahead where the configuration (i.e., the contents of theFIC) will change. The next super-frame with changes in the configurationis indicated by the value signaled within this field. If this field isset to the value ‘0000’, it means that no scheduled change is foreseen:e.g. value ‘0001’ indicates that there is a change in the nextsuper-frame.

RESERVED: This 16-bit field is reserved for future use.

The following fields appear in the loop over NUM_DP, which describe theparameters associated with the DP carried in the current frame.

DP_ID: This 6-bit field indicates uniquely the DP within a PHY profile.

DP_START: This 15-bit (or 13-bit) field indicates the start position ofthe first of the DPs using the DPU addressing scheme. The DP_START fieldhas differing length according to the PHY profile and FFT size as shownin the below table 27.

TABLE 27 DP_START field size PHY profile 64K 16K Base 13 bit 15 bitHandheld — 13 bit Advanced 13 bit 15 bit

DP_NUM_BLOCK: This 10-bit field indicates the number of FEC blocks inthe current TI group for the current DP. The value of DP_NUM_BLOCKranges from 0 to 1023

RESERVED: This 8-bit field is reserved for future use.

The following fields indicate the FIC parameters associated with theEAC.

EAC_FLAG: This 1-bit field indicates the existence of the EAC in thecurrent frame. This bit is the same value as the EAC_FLAG in thepreamble.

EAS_WAKE_UP_VERSION_NUM: This 8-bit field indicates the version numberof a wake-up indication.

If the EAC_FLAG field is equal to ‘1’, the following 12 bits areallocated for EAC_LENGTH_BYTE field. If the EAC_FLAG field is equal to‘0’, the following 12 bits are allocated for EAC_COUNTER.

EAC_LENGTH_BYTE: This 12-bit field indicates the length, in byte, of theEAC.

EAC_COUNTER: This 12-bit field indicates the number of the frames beforethe frame where the EAC arrives.

The following field appears only if the AUX_FLAG field is equal to ‘1’:

AUX_PRIVATE_DYN: This 48-bit field is reserved for future use forsignaling auxiliary streams. The meaning of this field depends on thevalue of AUX_STREAM_TYPE in the configurable PLS2-STAT.

CRC_32: A 32-bit error detection code, which is applied to the entirePLS2.

FIG. 16 illustrates a logical structure of a frame according to anembodiment of the present invention.

As above mentioned, the PLS, EAC, FIC, DPs, auxiliary streams and dummycells are mapped into the active carriers of the OFDM symbols in theframe. The PLS1 and PLS2 are first mapped into one or more FSS(s). Afterthat, EAC cells, if any, are mapped immediately following the PLS field,followed next by FIC cells, if any. The DPs are mapped next after thePLS or EAC, FIC, if any. Type 1 DPs follows first, and Type 2 DPs next.The details of a type of the DP will be described later. In some case,DPs may carry some special data for EAS or service signaling data. Theauxiliary stream or streams, if any, follow the DPs, which in turn arefollowed by dummy cells. Mapping them all together in the abovementioned order, i.e. PLS, EAC, FIC, DPs, auxiliary streams and dummydata cells exactly fill the cell capacity in the frame.

FIG. 17 illustrates PLS mapping according to an embodiment of thepresent invention.

PLS cells are mapped to the active carriers of FSS(s). Depending on thenumber of cells occupied by PLS, one or more symbols are designated asFSS(s), and the number of FSS(s) NFSS is signaled by NUM_FSS in PLS1.The FSS is a special symbol for carrying PLS cells. Since robustness andlatency are critical issues in the PLS, the FSS(s) has higher density ofpilots allowing fast synchronization and frequency-only interpolationwithin the FSS.

PLS cells are mapped to active carriers of the NFSS FSS(s) in a top-downmanner as shown in an example in FIG. 17. The PLS1 cells are mappedfirst from the first cell of the first FSS in an increasing order of thecell index. The PLS2 cells follow immediately after the last cell of thePLS1 and mapping continues downward until the last cell index of thefirst FSS. If the total number of required PLS cells exceeds the numberof active carriers of one FSS, mapping proceeds to the next FSS andcontinues in exactly the same manner as the first FSS.

After PLS mapping is completed, DPs are carried next. If EAC, FIC orboth are present in the current frame, they are placed between PLS and“normal” DPs.

FIG. 18 illustrates EAC mapping according to an embodiment of thepresent invention.

EAC is a dedicated channel for carrying EAS messages and links to theDPs for EAS. EAS support is provided but EAC itself may or may not bepresent in every frame. EAC, if any, is mapped immediately after thePLS2 cells. EAC is not preceded by any of the FIC, DPs, auxiliarystreams or dummy cells other than the PLS cells. The procedure ofmapping the EAC cells is exactly the same as that of the PLS.

The EAC cells are mapped from the next cell of the PLS2 in increasingorder of the cell index as shown in the example in FIG. 18. Depending onthe EAS message size, EAC cells may occupy a few symbols, as shown inFIG. 18.

EAC cells follow immediately after the last cell of the PLS2, andmapping continues downward until the last cell index of the last FSS. Ifthe total number of required EAC cells exceeds the number of remainingactive carriers of the last FSS mapping proceeds to the next symbol andcontinues in exactly the same manner as FSS(s). The next symbol formapping in this case is the normal data symbol, which has more activecarriers than a FSS.

After EAC mapping is completed, the FIC is carried next, if any exists.If FIC is not transmitted (as signaled in the PLS2 field), DPs followimmediately after the last cell of the EAC.

FIG. 19 illustrates FIC mapping according to an embodiment of thepresent invention.

shows an example mapping of FIC cell without EAC and (b) shows anexample mapping of FIC cell with EAC.

FIC is a dedicated channel for carrying cross-layer information toenable fast service acquisition and channel scanning. This informationprimarily includes channel binding information between DPs and theservices of each broadcaster. For fast scan, a receiver can decode FICand obtain information such as broadcaster ID, number of services, andBASE_DP_ID. For fast service acquisition, in addition to FIC, base DPcan be decoded using BASE_DP_ID. Other than the content it carries, abase DP is encoded and mapped to a frame in exactly the same way as anormal DP. Therefore, no additional description is required for a baseDP. The FIC data is generated and consumed in the Management Layer. Thecontent of FIC data is as described in the Management Layerspecification.

The FIC data is optional and the use of FIC is signaled by the FIC_FLAGparameter in the static part of the PLS2. If FIC is used, FIC_FLAG isset to ‘1’ and the signaling field for FIC is defined in the static partof PLS2. Signaled in this field are FIC_VERSION, and FIC_LENGTH_BYTE.FIC uses the same modulation, coding and time interleaving parameters asPLS2. FIC shares the same signaling parameters such as PLS2_MOD andPLS2_FEC. FIC data, if any, is mapped immediately after PLS2 or EAC ifany. FIC is not preceded by any normal DPs, auxiliary streams or dummycells. The method of mapping FIC cells is exactly the same as that ofEAC which is again the same as PLS.

Without EAC after PLS, FIC cells are mapped from the next cell of thePLS2 in an increasing order of the cell index as shown in an example in(a). Depending on the FIC data size, FIC cells may be mapped over a fewsymbols, as shown in (b).

FIC cells follow immediately after the last cell of the PLS2, andmapping continues downward until the last cell index of the last FSS. Ifthe total number of required FIC cells exceeds the number of remainingactive carriers of the last FSS, mapping proceeds to the next symbol andcontinues in exactly the same manner as FSS(s). The next symbol formapping in this case is the normal data symbol which has more activecarriers than a FSS.

If EAS messages are transmitted in the current frame, EAC precedes FIC,and FIC cells are mapped from the next cell of the EAC in an increasingorder of the cell index as shown in (b).

After FIC mapping is completed, one or more DPs are mapped, followed byauxiliary streams, if any, and dummy cells.

FIG. 20 illustrates a type of DP according to an embodiment of thepresent invention.

shows type 1 DP and (b) shows type 2 DP.

After the preceding channels, i.e., PLS, EAC and FIC, are mapped, cellsof the DPs are mapped. A DP is categorized into one of two typesaccording to mapping method:

Type 1 DP: DP is mapped by TDM

Type 2 DP: DP is mapped by FDM

The type of DP is indicated by DP_TYPE field in the static part of PLS2.FIG. 20 illustrates the mapping orders of Type 1 DPs and Type 2 DPs.Type 1 DPs are first mapped in the increasing order of cell index, andthen after reaching the last cell index, the symbol index is increasedby one. Within the next symbol, the DP continues to be mapped in theincreasing order of cell index starting from p=0. With a number of DPsmapped together in one frame, each of the Type 1 DPs are grouped intime, similar to TDM multiplexing of DPs.

Type 2 DPs are first mapped in the increasing order of symbol index, andthen after reaching the last OFDM symbol of the frame, the cell indexincreases by one and the symbol index rolls back to the first availablesymbol and then increases from that symbol index. After mapping a numberof DPs together in one frame, each of the Type 2 DPs are grouped infrequency together, similar to FDM multiplexing of DPs.

Type 1 DPs and Type 2 DPs can coexist in a frame if needed with onerestriction; Type 1 DPs always precede Type 2 DPs. The total number ofOFDM cells carrying Type 1 and Type 2 DPs cannot exceed the total numberof OFDM cells available for transmission of DPs:

D _(DP1) +D _(DP2) ≤D _(DP)  [Expression 2]

where DDP1 is the number of OFDM cells occupied by Type 1 DPs, DDP2 isthe number of cells occupied by Type 2 DPs. Since PLS, EAC, FIC are allmapped in the same way as Type 1 DP, they all follow “Type 1 mappingrule”. Hence, overall, Type 1 mapping always precedes Type 2 mapping.

FIG. 21 illustrates DP mapping according to an embodiment of the presentinvention.

shows an addressing of OFDM cells for mapping type 1 DPs and (b) showsan addressing of OFDM cells for mapping for type 2 DPs.

Addressing of OFDM cells for mapping Type 1 DPs (0, . . . , DDP1−1) isdefined for the active data cells of Type 1 DPs. The addressing schemedefines the order in which the cells from the TIs for each of the Type 1DPs are allocated to the active data cells. It is also used to signalthe locations of the DPs in the dynamic part of the PLS2.

Without EAC and FIC, address 0 refers to the cell immediately followingthe last cell carrying PLS in the last FSS. If EAC is transmitted andFIC is not in the corresponding frame, address 0 refers to the cellimmediately following the last cell carrying EAC. If FIC is transmittedin the corresponding frame, address 0 refers to the cell immediatelyfollowing the last cell carrying FIC. Address 0 for Type 1 DPs can becalculated considering two different cases as shown in (a). In theexample in (a), PLS, EAC and FIC are assumed to be all transmitted.Extension to the cases where either or both of EAC and FIC are omittedis straightforward. If there are remaining cells in the FSS aftermapping all the cells up to FIC as shown on the left side of (a).

Addressing of OFDM cells for mapping Type 2 DPs (0, . . . , DDP2−1) isdefined for the active data cells of Type 2 DPs. The addressing schemedefines the order in which the cells from the TIs for each of the Type 2DPs are allocated to the active data cells. It is also used to signalthe locations of the DPs in the dynamic part of the PLS2.

Three slightly different cases are possible as shown in (b). For thefirst case shown on the left side of (b), cells in the last FSS areavailable for Type 2 DP mapping. For the second case shown in themiddle, FIC occupies cells of a normal symbol, but the number of FICcells on that symbol is not larger than CFSS. The third case, shown onthe right side in (b), is the same as the second case except that thenumber of FIC cells mapped on that symbol exceeds CFSS.

The extension to the case where Type 1 DP(s) precede Type 2 DP(s) isstraightforward since PLS, EAC and FIC follow the same “Type 1 mappingrule” as the Type 1 DP(s).

A data pipe unit (DPU) is a basic unit for allocating data cells to a DPin a frame.

A DPU is defined as a signaling unit for locating DPs in a frame. A CellMapper 7010 may map the cells produced by the TIs for each of the DPs. ATime interleaver 5050 outputs a series of TI-blocks and each TI-blockcomprises a variable number of XFECBLOCKs which is in turn composed of aset of cells. The number of cells in an XFECBLOCK, Ncells, is dependenton the FECBLOCK size, Nldpc, and the number of transmitted bits perconstellation symbol. A DPU is defined as the greatest common divisor ofall possible values of the number of cells in a XFECBLOCK, Ncells,supported in a given PHY profile. The length of a DPU in cells isdefined as LDPU. Since each PHY profile supports different combinationsof FECBLOCK size and a different number of bits per constellationsymbol, LDPU is defined on a PHY profile basis.

FIG. 22 illustrates an FEC structure according to an embodiment of thepresent invention.

FIG. 22 illustrates an FEC structure according to an embodiment of thepresent invention before bit interleaving. As above mentioned, Data FECencoder may perform the FEC encoding on the input BBF to generateFECBLOCK procedure using outer coding (BCH), and inner coding (LDPC).The illustrated FEC structure corresponds to the FECBLOCK. Also, theFECBLOCK and the FEC structure have same value corresponding to a lengthof LDPC codeword.

The BCH encoding is applied to each BBF (Kbch bits), and then LDPCencoding is applied to BCH-encoded BBF (Kldpc bits=Nbch bits) asillustrated in FIG. 22.

The value of Nldpc is either 64800 bits (long FECBLOCK) or 16200 bits(short FECBLOCK).

The below table 28 and table 29 show FEC encoding parameters for a longFECBLOCK and a short FECBLOCK, respectively.

TABLE 28 BCH error LDPC correction Rate N_(ldpc) K_(ldpc) K_(bch)capability N_(bch)-K_(bch)  5/15 64800 21600 21408 12 192  6/15 2592025728  7/15 30240 30048  8/15 34560 34368  9/15 38880 38688 10/15 4320043008 11/15 47520 47328 12/15 51840 51648 13/15 56160 55968

TABLE 29 BCH error LDPC correction Rate N_(ldpc) K_(ldpc) K_(bch)capability N_(bch)-K_(bch)  5/15 16200 5400 5232 12 168  6/15 6480 6312 7/15 7560 7392  8/15 8640 8472  9/15 9720 9552 10/15 10800 10632 11/1511880 11712 12/15 12960 12792 13/15 14040 13872

The details of operations of the BCH encoding and LDPC encoding are asfollows:

A 12-error correcting BCH code is used for outer encoding of the BBF.The BCH generator polynomial for short FECBLOCK and long FECBLOCK areobtained by multiplying together all polynomials.

LDPC code is used to encode the output of the outer BCH encoding. Togenerate a completed Bldpc (FECBLOCK), Pldpc (parity bits) is encodedsystematically from each Ildpc (BCH-encoded BBF), and appended to Ildpc.The completed Bldpc (FECBLOCK) are expressed as follow expression.

B _(ldpc)=[I _(ldpc) P _(ldpc)]=[i ₀ ,i ₁ , . . . ,i _(K) _(ldpc) ₋₁ ,p₀ ,p ₁ , . . . ,p _(N) _(ldpc) _(-K) _(ldpc) ₋₁]  [expression 3]

The parameters for long FECBLOCK and short FECBLOCK are given in theabove table 28 and 29, respectively.

The detailed procedure to calculate Nldpc−Kldpc parity bits for longFECBLOCK, is as follows:

1) Initialize the parity bits,

p ₀ =p ₁ =p ₂ = . . . =p _(N) _(ldpc) _(-K) _(ldpc) ₋₁=0  [expression 4]

2) Accumulate the first information bit—i0, at parity bit addressesspecified in the first row of an addresses of parity check matrix. Thedetails of addresses of parity check matrix will be described later. Forexample, for rate 13/15:

$\begin{matrix}\begin{matrix}{{p_{983} = {p_{983} \oplus i_{0}}}\mspace{40mu}} & {p_{2815} = {p_{2815} \oplus i_{0}}} \\{{p_{4837} = {p_{4837} \oplus i_{0}}}\mspace{25mu}} & {p_{4989} = {p_{4989} \oplus i_{0}}} \\{{p_{6138} = {p_{6138} \oplus i_{0}}}\mspace{25mu}} & {p_{6458} = {p_{6458} \oplus i_{0}}} \\{{p_{6921} = {p_{6921} \oplus i_{0}}}\mspace{25mu}} & {p_{6974} = {p_{6974} \oplus i_{0}}} \\{{p_{7572} = {p_{7572} \oplus i_{0}}}\mspace{25mu}} & {p_{8260} = {p_{8260} \oplus i_{0}}} \\{{p_{8496} = {p_{8496} \oplus i_{0}}}\mspace{31mu}} & \;\end{matrix} & \left\lbrack {{expression}\mspace{14mu} 5} \right\rbrack\end{matrix}$

3) For the next 359 information bits, is, s=1, 2, . . . , 359 accumulateis at parity bit addresses using following expression.

{x+(s mod 360)×Q _(ldpc)}mod(N _(ldpc) −K _(ldpc))  [expression 6]

where x denotes the address of the parity bit accumulator correspondingto the first bit i0, and Qldpc is a code rate dependent constantspecified in the addresses of parity check matrix. Continuing with theexample, Qldpc=24 for rate 13/15, so for information bit i1, thefollowing operations are performed:

$\begin{matrix}\begin{matrix}{{p_{1007} = {p_{1007} \oplus i_{1}}}\mspace{34mu}} & {p_{2839} = {p_{2839} \oplus i_{1}}} \\{{p_{4861} = {p_{4861} \oplus i_{1}}}\mspace{25mu}} & {p_{5013} = {p_{5013} \oplus i_{1}}} \\{{p_{6162} = {p_{6162} \oplus i_{1}}}\mspace{25mu}} & {p_{6482} = {p_{6482} \oplus i_{1}}} \\{{p_{6945} = {p_{6945} \oplus i_{1}}}\mspace{25mu}} & {p_{6998} = {p_{6998} \oplus i_{1}}} \\{{p_{7596} = {p_{7572} \oplus i_{1}}}\mspace{25mu}} & {p_{8284} = {p_{8284} \oplus i_{1}}} \\{{p_{8520} = {p_{8520} \oplus i_{1}}}\mspace{31mu}} & \;\end{matrix} & \left\lbrack {{expression}\mspace{14mu} 7} \right\rbrack\end{matrix}$

4) For the 361st information bit i360, the addresses of the parity bitaccumulators are given in the second row of the addresses of paritycheck matrix. In a similar manner the addresses of the parity bitaccumulators for the following 359 information bits is, s=361, 362, . .. , 719 are obtained using the expression 6, where x denotes the addressof the parity bit accumulator corresponding to the information bit i360,i.e., the entries in the second row of the addresses of parity checkmatrix.

5) In a similar manner, for every group of 360 new information bits, anew row from addresses of parity check matrixes used to find theaddresses of the parity bit accumulators.

After all of the information bits are exhausted, the final parity bitsare obtained as follows:

6) Sequentially perform the following operations starting with i=1

p _(i) =p _(i) ⊕p _(i-1) ,i=1,2, . . . ,N _(ldpc) −K _(ldpc)−1  [MathFIG. 8]

where final content of pi, i=0, 1, . . . Nldpc−Kldpc−1 is equal to theparity bit pi.

TABLE 30 Code Rate Q_(ldpc)  5/15 120  6/15 108  7/15 96  8/15 84  9/1572 10/15 60 11/15 48 12/15 36 13/15 24

This LDPC encoding procedure for a short FECBLOCK is in accordance witht LDPC encoding procedure for the long FECBLOCK, except replacing thetable 30 with table 31, and replacing the addresses of parity checkmatrix for the long FECBLOCK with the addresses of parity check matrixfor the short FECBLOCK.

TABLE 31 Code Rate Q_(ldpc)  5/15 30  6/15 27  7/15 24  8/15 21  9/15 1810/15 15 11/15 12 12/15 9 13/15 6

FIG. 23 illustrates a bit interleaving according to an embodiment of thepresent invention.

The outputs of the LDPC encoder are bit-interleaved, which consists ofparity interleaving followed by Quasi-Cyclic Block (QCB) interleavingand inner-group interleaving.

shows Quasi-Cyclic Block (QCB) interleaving and (b) shows inner-groupinterleaving.

The FECBLOCK may be parity interleaved. At the output of the parityinterleaving, the LDPC codeword consists of 180 adjacent QC blocks in along FECBLOCK and 45 adjacent QC blocks in a short FECBLOCK. Each QCblock in either a long or short FECBLOCK consists of 360 bits. Theparity interleaved LDPC codeword is interleaved by QCB interleaving. Theunit of QCB interleaving is a QC block. The QC blocks at the output ofparity interleaving are permutated by QCB interleaving as illustrated inFIG. 23, where Ncells=64800/η mod or 16200/η mod according to theFECBLOCK length. The QCB interleaving pattern is unique to eachcombination of modulation type and LDPC code rate.

After QCB interleaving, inner-group interleaving is performed accordingto modulation type and order (η mod) which is defined in the below table32. The number of QC blocks for one inner-group, NQCB_IG, is alsodefined.

TABLE 32 Modulation type η_(mod) N_(QCB)_IG QAM-16 4 2 NUC-16 4 4 NUQ-646 3 NUC-64 6 6 NUQ-256 8 4 NUC-256 8 8 NUQ-1024 10 5 NUC-1024 10 10

The inner-group interleaving process is performed with NQCB_IG QC blocksof the QCB interleaving output. Inner-group interleaving has a processof writing and reading the bits of the inner-group using 360 columns andNQCB_IG rows. In the write operation, the bits from the QCB interleavingoutput are written row-wise. The read operation is performed column-wiseto read out m bits from each row, where m is equal to 1 for NUC and 2for NUQ.

FIG. 24 illustrates a cell-word demultiplexing according to anembodiment of the present invention.

FIG. 24 shows a cell-word demultiplexing for 8 and 12 bpcu MIMO and (b)shows a cell-word demultiplexing for 10 bpcu MIMO.

Each cell word (c0,1, c1,1, . . . , cη mod−1,1) of the bit interleavingoutput is demultiplexed into (d1,0,m, d1,1,m . . . , d1,η mod−1,m) and(d2,0,m, d2,1,m . . . , d2,η mod−1,m) as shown in (a), which describesthe cell-word demultiplexing process for one XFECBLOCK.

For the 10 bpcu MIMO case using different types of NUQ for MIMOencoding, the Bit Interleaver for NUQ-1024 is re-used. Each cell word(c0,1, c1,1, . . . , c9,1) of the Bit Interleaver output isdemultiplexed into (d1,0,m, d1,1,m . . . , d1,3,m) and (d2,0,m, d2,1,m .. . , d2,5,m), as shown in (b).

FIG. 25 illustrates a time interleaving according to an embodiment ofthe present invention.

to (c) show examples of TI mode.

The time interleaver operates at the DP level. The parameters of timeinterleaving (TI) may be set differently for each DP.

The following parameters, which appear in part of the PLS2-STAT data,configure the TI:

DP_TI_TYPE (allowed values: 0 or 1): Represents the TI mode; ‘0’indicates the mode with multiple TI blocks (more than one TI block) perTI group. In this case, one TI group is directly mapped to one frame (nointer-frame interleaving). ‘1’ indicates the mode with only one TI blockper TI group. In this case, the TI block may be spread over more thanone frame (inter-frame interleaving).

DP_TI_LENGTH: If DP_TI_TYPE=‘0’, this parameter is the number of TIblocks NTI per TI group. For DP_TI_TYPE=‘1’, this parameter is thenumber of frames PI spread from one TI group.

DP_NUM_BLOCK_MAX (allowed values: 0 to 1023): Represents the maximumnumber of XFECBLOCKs per TI group.

DP_FRAME_INTERVAL (allowed values: 1, 2, 4, 8): Represents the number ofthe frames IJUMP between two successive frames carrying the same DP of agiven PHY profile.

DP_TI_BYPASS (allowed values: 0 or 1): If time interleaving is not usedfor a DP, this parameter is set to ‘1’. It is set to ‘0’ if timeinterleaving is used.

Additionally, the parameter DP_NUM_BLOCK from the PLS2-DYN data is usedto represent the number of XFECBLOCKs carried by one TI group of the DP.

When time interleaving is not used for a DP, the following TI group,time interleaving operation, and TI mode are not considered. However,the Delay Compensation block for the dynamic configuration informationfrom the scheduler will still be required. In each DP, the XFECBLOCKsreceived from the SSD/MIMO encoding are grouped into TI groups. That is,each TI group is a set of an integer number of XFECBLOCKs and willcontain a dynamically variable number of XFECBLOCKs. The number ofXFECBLOCKs in the TI group of index n is denoted by NxBLOCK_Group(n) andis signaled as DP_NUM_BLOCK in the PLS2-DYN data. Note thatNxBLOCK_Group(n) may vary from the minimum value of 0 to the maximumvalue NxBLOCK_Group_MAX (corresponding to DP_NUM_BLOCK_MAX) of which thelargest value is 1023.

Each TI group is either mapped directly onto one frame or spread over PIframes. Each TI group is also divided into more than one TI blocks(NTI),where each TI block corresponds to one usage of time interleaver memory.The TI blocks within the TI group may contain slightly different numbersof XFECBLOCKs. If the TI group is divided into multiple TI blocks, it isdirectly mapped to only one frame. There are three options for timeinterleaving (except the extra option of skipping the time interleaving)as shown in the below table 33.

TABLE 33 Modes Descriptions Option-1 Each TI group contains one TI blockand is mapped directly to one frame as shown in (a). This option issignaled in the PLS2-STAT by DP_TI_TYPE = ‘0’ and DP_TI_ LENGTH =‘1’(N_(TI) = 1). Option-2 Each TI group contains one TI block and ismapped to more than one frame. (b) shows an example, where one TI groupis mapped to two frames, i.e., DP_TI_LENGTH = ‘2’ (P_(I) = 2) andDP_FRAME_INTERVAL (I_(JUMP) = 2). This provides greater time diversityfor low data-rate services. This option is signaled in the PLS2-STAT byDP_TI_TYPE = ‘1’. Option-3 Each TI group is divided into multiple TIblocks and is mapped directly to one frame as shown in (c). Each TIblock may use full TI memory, so as to provide the maximum bit-rate fora DP. This option is signaled in the PLS2-STAT signaling by DP_TI_TYPE =‘0’ and DP_TI_ LENGTH = N_(TI), while P_(I) = 1.

In each DP, the TI memory stores the input XFECBLOCKs (output XFECBLOCKsfrom the SSD/MIMO encoding block). Assume that input XFECBLOCKs aredefined as

(d_(n,s,0,0), d_(n,s,0,1), . . . , d_(n,s,0,N) _(cells) ₋₁, d_(n,s,1,0),. . . , d_(n,s,l,N) _(cells) ₋₁, . . . , d_(n,s,N) _(xBLOCK_TI)_((n,s)-1,0), . . . , d_(n,s,N) _(xBLOCK_TI) _((n,s)- 1,N) _(cells) ₋₁),

where d_(n,s,r,q) is the qth cell of the rth XFECBLOCK in the sth TIblock of the nth TI group

and represents the outputs of SSD and MIMO encodings as follows

$d_{n,s,r,q} = \left\{ {\begin{matrix}{f_{n,s,r,q},} & {{the}\mspace{14mu} {output}\mspace{14mu} {of}\mspace{14mu} {{SSD}\mspace{14mu}.\;.\;.\mspace{14mu} {encoding}}} \\{g_{n,s,r,q},} & {{the}\mspace{14mu} {output}\mspace{14mu} {of}\mspace{14mu} {MIMO}\mspace{14mu} {encoding}}\end{matrix}.} \right.$

In addition, assume that output XFECBLOCKs from the time interleaver5050 are defined as

(h_(n,s,0), h_(n,s,1), . . . h_(n,s,i), . . . , h_(n,s,N) _(xBLOCK_TI)_((n,s)×N) _(cells) ₋₁),

where h_(n,s,i) is the ith output cell (for i=0, . . . ,N_(xBLOCK_TI)(n,s)×N_(cells)−1) in the sth TI block of the nth TI group.

Typically, the time interleaver will also act as a buffer for DP dataprior to the process of frame building. This is achieved by means of twomemory banks for each DP. The first TI-block is written to the firstbank. The second TI-block is written to the second bank while the firstbank is being read from and so on.

The TI is a twisted row-column block interleaver. For the sth TI blockof the nth TI group, the number of rows N_(r) of a TI memory is equal tothe number of cells N_(cells), i.e., N_(r)=N_(cells) while the number ofcolumns N_(c) is equal to the number N_(xBLOCK_TI) (n,s).

FIG. 26 illustrates the basic operation of a twisted row-column blockinterleaver according to an embodiment of the present invention.

FIG. 26(a) shows a writing operation in the time interleaver and FIG.26(b) shows a reading operation in the time interleaver The firstXFECBLOCK is written column-wise into the first column of the TI memory,and the second XFECBLOCK is written into the next column, and so on asshown in (a). Then, in the interleaving array, cells are read outdiagonal-wise. During diagonal-wise reading from the first row(rightwards along the row beginning with the left-most column) to thelast row, N_(r) cells are read out as shown in (b). In detail, assumingz_(n,s,i) (i=0, . . . ,N_(r)N_(c)) as the TI memory cell position to beread sequentially, the reading process in such an interleaving array isperformed by calculating the row index R_(n,s,i), the column indexC_(n,s,i), and the associated twisting parameter T_(n,s,i) as followsexpression.

$\begin{matrix}{{{GENERATE}\left( {R_{n,s,i},C_{n,s,i}} \right)} = \left\{ {{R_{n,s,i} = {{mod}\left( {i,N_{r}} \right)}},{T_{n,s,i} = {{mod}\left( {{S_{shift} \times R_{n,s,i}},N_{c}} \right)}},{C_{n,s,i} = {{mod}\left( {{T_{n,s,i} + \left\lfloor \frac{i}{N_{r}} \right\rfloor},N_{c}} \right)}}} \right\}} & \left\lbrack {{expression}\mspace{14mu} 9} \right\rbrack\end{matrix}$

where S_(shift) if is a common shift value for the diagonal-wise readingprocess regardless of N_(xBLOCK_TI)(n,s), and it is determined byN_(xBLOCK_TI_MAX) given in the PLS2-STAT as follows expression.

${for}\left\{ {\begin{matrix}{\begin{matrix}{N_{{xBLOCK\_ TI}{\_ MAX}}^{\prime} =} \\{N_{{xBLOCK\_ TI}{\_ MAX}} + 1}\end{matrix},} & {{{if}\mspace{14mu} N_{{xBLOCK\_ TI}{\_ MAX}}{mod2}} = 0} \\{\begin{matrix}{N_{{xBLOCK\_ TI}{\_ MAX}}^{\prime} =} \\N_{{xBLOCK\_ TI}{\_ MAX}}\end{matrix},} & {{{if}\mspace{14mu} N_{{xBLOCK\_ TI}{\_ MAX}}{mod2}} = 1}\end{matrix},{{\left\lbrack {{expression}\mspace{14mu} 10} \right\rbrack \mspace{20mu} S_{shift}} = \frac{N_{{xBLOCK\_ TI}{\_ MAX}}^{\prime} - 1}{2}}} \right.$

As a result, the cell positions to be read are calculated by acoordinate as z_(n,s,i)=N_(r)C_(n,s,i)+R_(n,s,i).

FIG. 27 illustrates an operation of a twisted row-column blockinterleaver according to another embodiment of the present invention.

More specifically, FIG. 27 illustrates the interleaving array in the TImemory for each TI group, including virtual XFECBLOCKs whenN_(xBLOCK_TI)(0,0)=3, N_(xBLOCK_TI) (1,0)=6, N_(xBLOCK_TI) (2,0)=5.

The variable number N_(xBLOCK TI)(n,s)=N_(r) will be less than or equalto N′_(xBLOCK_TI_MAX). Thus, in order to achieve a single-memorydeinterleaving at the receiver side, regardless of N_(xBLOCK_TI)(n,s),the interleaving array for use in a twisted row-column block interleaveris set to the size of N_(r)N_(c)=N_(cells)×N′_(xBLOCK TI MAX) byinserting the virtual XFECBLOCKs into the TI memory and the readingprocess is accomplished as follow expression.

$\begin{matrix}{{{p = 0};}{{{{for}\mspace{14mu} i} = 0};{i < {N_{cells}N_{{xBLOCK\_ TI}{\_ MAX}}^{\prime}}};{i = {i + 1}}}\left\{ {{{GENERATE}\mspace{14mu} \left( {R_{n,s,i},C_{n,s,i}} \right)};{V_{i} = {{{N_{r}C_{n,s,j}} + {R_{n,s,j}\mspace{25mu} {if}\mspace{14mu} V_{i}}} < {N_{cells}{N_{xBLOC\_ TI}\left( {n,s} \right)}\mspace{25mu} \left\{ \mspace{50mu} {{Z_{n,s,p} = V_{i}};{p = {p + 1}};}\mspace{50mu} \right\}}}}} \right\}} & \lbrack{expression11}\rbrack\end{matrix}$

The number of TI groups is set to 3. The option of time interleaver issignaled in the PLS2-STAT data by DP_TI_TYPE=‘0’, DP_FRAME_INTERVAL=‘1’,and DP_TI_LENGTH=‘1’, i.e., NTI=1, IJUMP=1, and PI=1. The number ofXFECBLOCKs, each of which has Ncells=30 cells, per TI group is signaledin the PLS2-DYN data by NxBLOCK_TI(0,0)=3, NxBLOCK_TI(1,0)=6, andNxBLOCK_TI(2,0)=5, respectively. The maximum number of XFECBLOCK issignaled in the PLS2-STAT data by NxBLOCK_Group_MAX, which leads to└N_(xBLOCK Group MAX)/N_(TI)┘=N_(xBLOCK TI MAX)=6.

FIG. 28 illustrates a diagonal-wise reading pattern of a twistedrow-column block interleaver according to an embodiment of the presentinvention.

More specifically FIG. 28 shows a diagonal-wise reading pattern fromeach interleaving array with parameters of N′_(xBLOCK_TI_MAX)=7 andSshift=(7−1)/2=3. Note that in the reading process shown as pseudocodeabove, if V_(i)≥N_(cells)N_(xBLOCK_TI)(n,s), the value of Vi is skippedand the next calculated value of Vi is used.

FIG. 29 illustrates interleaved XFECBLOCKs from each interleaving arrayaccording to an embodiment of the present invention.

FIG. 29 illustrates the interleaved XFECBLOCKs from each interleavingarray with parameters of N′_(xBLOCK_TI_MAX)=7 and Sshift=3.

FIG. 30 illustrates a time interleaving process according to anembodiment of the present invention.

As described above, a timer interleaver (or time interleaver block)included in a broadcast signal transmitter according to an embodiment ofthe present invention interleaves cells belonging to a plurality of FECblocks in the time domain and outputs the interleaved cells.

TI group is a unit over which dynamic capacity allocation for aparticular DP is carried out, made up of an integer, dynamically varyingnumber of FEC blocks. Time interleaving block (TI block) is a set ofcells within which time interleaving is carried out, corresponding toone use of the time interleaver memory. FEC block may be a set ofencoded bits of a DP data or a set of number of cells carrying all theencoded bits.

Each TI group is either mapped directly onto one frame or spread overmultiple frames. Each TI group is also divided into more than one TIblocks, where each TI block corresponds to one usage of time interleavermemory. The TI blocks within the TI group may contain slightly differentnumbers of FECBLOCKs.

The cells of the FEC blocks are transmitted being distributed in aspecific period corresponding to a time interleaving depth through timeinterleaving, and thus diversity gain can be obtained. The timeinterleaver according to an embodiment of the present invention operatesat the DP level.

In addition, the time interleaver according to an embodiment of thepresent invention can perform time interleaving including a writingoperation of sequentially arranging different input FEC blocks in apredetermined memory and a diagonal reading operation of interleavingthe FEC blocks in a diagonal direction. Time interleaving according toan embodiment of the present invention may be referred to asdiagonal-type time interleaving or diagonal-type TI.

Typically, the time interleaver will also act as a buffer for DP dataprior to the process of frame building. This is achieved by means of twomemory banks for each DP. The first TI-block is written to the firstbank. The second TI-block is written to the second bank while the firstbank is being read from and so on.

The name of a device which performs time interleaving or the location orfunction of the device may be changed according to designer.

A TI block according to an embodiment may be composed of Nc FEC blocksand the length of an FEC block may be assumed to be Nr×1. Accordingly, aTI memory according to an embodiment of the present invention can have asize corresponding to an Nr×Nc matrix. In addition, the depth of timeinterleaving according to an embodiment of the present inventioncorresponds to the FEC block length. FIG. 30(a) shows a writingdirection of time interleaving according to an embodiment of the presentinvention and FIG. 30(b) shows a reading direction of time interleavingaccording to an embodiment of the present invention.

Specifically, the broadcast signal transmitter according to anembodiment of the present invention can sequentially write input FECblocks column-wise in a TI memory having a size of Nr×Nc (column-wisewriting), as shown in FIG. 30(a). The first FECBLOCK 0 is writtencolumn-wise into the first column of the TI memory, and the secondFECBLOCK 1 is written in the next column, and so on.

The broadcast signal transmitter according to an embodiment of thepresent invention can read the FEC blocks written column-wise in adiagonal direction, as shown in FIG. 30(b). In this case, the broadcastsignal transmitter according to an embodiment of the present inventioncan perform diagonal reading for one period.

That is, during diagonal-wise reading from the first row (rightwardsalong the row beginning with the left-most column) to the last row,cells are read out as shown in FIG. 30(b).

Particularly, since the diagonal reading process of the first periodstarts at (0,0) of the memory matrix and is performed until the cell ofthe lowest row is read, cells within different FEC blocks can beuniformly interleaved. Diagonal reading of the next periods can beperformed in order of {circle around (1)}, {circle around (2)} and{circle around (3)} in FIG. 30(b).

FIG. 31 illustrates a time interleaving process according to anotherembodiment of the present invention.

FIG. 31 shows another embodiment of the aforementioned writing operationand reading operation of the diagonal-type TI.

One TI block according to an embodiment of the present inventionincludes 4 FEC blocks each of which may be composed of 8 cells.Accordingly, the TI memory has a size corresponding to an 8×4 (or 32×1)matrix and the column length and row length of the TI memoryrespectively correspond to the FEC block length (or time interleavingdepth) and the number of FECs.

TI input FEC blocks shown in the left part of FIG. 31 are FEC blockssequentially input to the time interleaver.

TI FEC blocks shown in the middle of FIG. 31 show n-th cell values of ani-th FEC block stored in the TI memory and TI memory indexes indicatethe order of cells of FEC blocks stored in the TI memory.

FIG. 31(a) illustrates TI writing operation. As described above,sequentially input FEC blocks can be sequentially written column-wiseinto the TI memory. Accordingly, cells of the FEC blocks aresequentially stored and written with TI memory indexes.

FIG. 31(b) illustrates TI reading operation. As shown in FIG. 31(b),cell values stored in the TI memory can be diagonally read and output inthe order of memory indexes 0, 9, 18, 27, . . . . Moreover a position ofcell to start diagonal-wise reading or diagonal-wise reading pattern maybe changed according to designer.

TI output FEC blocks shown in the right part of FIG. 31 sequentiallyindicate cell values output through diagonal-type TI according to anembodiment of the present invention. TI output memory indexes correspondto the cell values output through diagonal-type TI.

Consequently, the time interleaver according to an embodiment of thepresent invention can perform diagonal-type TI by sequentiallygenerating TI output memory indexes for sequentially input FEC blocks.

FIG. 32 illustrates a process of generating TI output memory indexesaccording to an embodiment of the present invention.

As described above, the time interleaver according to an embodiment ofthe present invention can perform diagonal-type TI by sequentiallygenerating TI output memory index values for sequentially input FECblocks.

FIG. 32(a) illustrates a process of generating diagonal-type TI memoryindexes for the above-described sequentially input FEC blocks and FIG.32(b) shows equations representing the memory index generation process.

A time deinterleaver (or time deinterleaver block) included in abroadcast signal receiver according to an embodiment of the presentinvention can perform inverse processing of the aforementioneddiagonal-type TI. That is, the time deinterleaver according to anembodiment of the present invention can perform time deinterleaving byreceiving FEC blocks on which diagonal-type TI has been performed,writing the FEC blocks diagonal-wise in a TI memory and thensequentially reading the FEC blocks. Time deinterleaving according to anembodiment of the present invention may be referred to as diagonal-typeTDI or diagonal-type time deinterleaving. The name of a deviceperforming time deinterleaving or the location or function of the devicemay be changed according to designer.

FIG. 33 illustrates a time deinterleaving process according to anembodiment of the present invention.

The time deinterleaving process shown in FIG. 33 corresponds to inverseprocessing of the time interleaving process shown in FIG. 30.

FIG. 33(a) shows a writing direction of time deinterleaving according toan embodiment of the present invention and FIG. 33(b) shows a readingdirection of time deinterleaving according to an embodiment of thepresent invention.

Specifically, the time deinterleaver according to an embodiment of thepresent invention can receive FEC blocks on which diagonal-type TI hasbeen performed from a transmitter and diagonally write the FEC blocksinto a TDI (time deinterleaver) memory (diagonal-wise writing).

In this case, the time deinterleaver according to an embodiment of thepresent invention can perform diagonal writing for one period.

Particularly, diagonal reading of the first period starts at (0,0) ofthe memory matrix and is performed until the cell of the lowest row isread. Diagonal writing of respective periods can be performed in orderof {circle around (1)}, {circle around (2)} and {circle around (3)} inFIG. 33(b).

As shown in FIG. 33(b), the time deinterleaver according to anembodiment of the present invention can sequentially read diagonallywritten FEC blocks column-wise (column-wise reading).

FIG. 34 illustrates a time deinterleaving process according to anotherembodiment of the present invention.

The time deinterleaving process shown in FIG. 34 is the inverse of thetime interleaving process shown in FIG. 31.

One TI block according to an embodiment of the present inventionincludes 4 FEC blocks each of which may be composed of 8 cells.Accordingly, the TI memory has a size corresponding to an 8×4 (or 32×1)matrix and the column length and row length of the TI memoryrespectively correspond to the FEC block length (or time interleavingdepth) and the number of FECs.

TDI input FEC blocks shown in the left part of FIG. 34 represent cellsof FEC blocks sequentially input to the time deinterleaver and TDI inputmemory indexes correspond to the cells of the sequentially input FECblocks.

TDI FEC blocks shown in the middle of FIG. 34 show n-th cell values ofan i-th FEC block stored in the TDI memory and TDI memory indexesindicate the order of cells of FEC blocks stored in the TDI memory.

FIG. 34(a) illustrates TDI writing operation. As described above,sequentially input FEC blocks can be sequentially written to the TDImemory diagonal-wise. Accordingly, the cells of the input FEC blocks aresequentially stored and written with TDI memory indexes.

FIG. 34(b) illustrates TDI reading operation. As shown in FIG. 34(b),cell values stored in the TDI memory can be column-wise read and outputin the order of memory indexes 0, 1, 2, 3, . . . .

TDI output FEC blocks shown in the right part of FIG. 34 sequentiallyindicate cell values output through time deinterleaving according to anembodiment of the present invention. TDI output memory indexescorrespond to the cell values output through time deinterleavingaccording to an embodiment of the present invention.

Consequently, the time deinterleaver according to an embodiment of thepresent invention can perform diagonal-type TDI by sequentiallygenerating TDI output memory index values for sequentially input FECblocks.

FIG. 35 illustrates a process of generating TDI output memory indexesaccording to an embodiment of the present invention.

As described above, the time deinterleaver according to an embodiment ofthe present invention can perform diagonal-type TDI by sequentiallygenerating TDI output memory index values for sequentially input FECblocks.

FIG. 35(a) illustrates a process of generating diagonal-type TDI memoryindexes for the above-described sequentially input FEC blocks and FIG.32(b) shows equations representing the memory index generation process.

The broadcast signal transmitter according to an embodiment of thepresent invention may be a variable data-rate system in which aplurality of FEC blocks is packed and configured as a plurality of TIblocks and transmitted. In this case, TI blocks may have differentnumbers of FEC blocks included therein.

FIG. 36 is a conceptual diagram illustrating a variable data-rate systemaccording to an embodiment of the present invention.

FIG. 36 shows TI blocks mapped to one signal frame.

As described above, the variable data-rate system as a broadcast signaltransmitter according to an embodiment of the present invention can packa plurality of FEC blocks as a plurality of TI blocks and transmit theTI blocks. In this case, the TI blocks may have different numbers of FECblocks included therein.

That is, one signal frame may include NTI_NUM TI blocks each of whichmay include NFEC_NUM FEC blocks. In this case, the respective TI blocksmay have different numbers of FEC blocks included therein.

A description will be given of time interleaving which can be performedin the aforementioned variable data-rate system. This time interleavingprocess is another embodiment of the above-described time interleavingprocess and has the advantage that the time interleaving process isapplicable to a case in which the broadcast signal receiver has a singlememory. Time interleaving according to another embodiment of the presentinvention may be referred to as the aforementioned diagonal-type TI andmay be performed in the time interleaver included in the broadcastsignal transmitter according to an embodiment of the present invention.As the inverse process of time interleaving, time deinterleaving may bereferred to as diagonal-type TDI and may be performed in the timedeinterleaver in the broadcast signal receiver according to anembodiment of the present invention. The name of a device which performstime interleaving or time deinterleaving or the location or function ofthe device may be changed according to designer. A description will begiven of detailed time interleaving and time deinterleaving operations.

When TI blocks have different numbers of FEC blocks included therein, asdescribed above, different diagonal-type TI methods need to be appliedto the respective TI blocks. However, this scheme has a problem thatdeinterleaving corresponding to the different diagonal-type TI methodscannot be performed when the broadcast signal receiver uses a singlememory.

Accordingly, the broadcast signal transmitter according to the presentinvention determines a single diagonal-type TI method and equallyapplies the determined diagonal-type TI method to all TI blocksaccording to an embodiment of the present invention. In addition, thebroadcast signal transmitter according to an embodiment of the presentinvention can sequentially deinterleave a plurality of TI blocks using asingle memory.

In this case, the broadcast signal transmitter according to anembodiment of the present invention can determine the diagonal-type TImethod applied to all TI blocks on the basis of a TI block including amaximum number of FEC blocks within one signal frame.

Moreover, the broadcast signal transmitter according to an embodiment ofthe present invention can determine the diagonal-type TI method appliedto all TI blocks on the basis of a TI block including a medium number ofFEC blocks within one signal frame or an arbitrary TI block within onesignal frame. It can be determined according to designer.

Here, how the diagonal-type TI method is applied to a TI block includinga smaller number of FEC blocks, compared to the TI block including themaximum number of FEC blocks, may become a problem.

Accordingly, the broadcast signal transmitter may monitor generatedmemory indexes and determine whether to apply the memory indexesaccording to an embodiment of the present invention.

Specifically, when the number of generated TI memory indexes exceeds thenumber of cells in an arbitrary TI block, the broadcast signaltransmitter ignores TI memory indexes greater than the number of cellsaccording to an embodiment of the present invention. When the number ofgenerated TI memory indexes exceeds the number of cells, virtual FECblocks can be added (zero padding) and diagonal-type TI can beperformed. Furthermore, in application of the aforementioneddiagonal-type TI method to different TI blocks, the broadcast signaltransmitter may sequentially apply the diagonal-type TI method to TIblocks from a TI block including a small number of FEC blocks in orderof the number of FEC blocks according to an embodiment of the presentinvention. Accordingly, the broadcast signal receiver according to anembodiment of the present invention can simply operate the singlememory, which will be described in detail later.

The following equation represents the aforementioned process ofdetermining a diagonal-type TI method applied to all TI blocks.

for  0 ≤ j ≤ TI_NUM − 1[Equation  12] $\begin{matrix}{N_{r} = {\max \left( {N_{{FEC\_ Size},0},{N_{{FEC\_ Size},0}\mspace{14mu}.\;.\;.}\mspace{14mu},N_{{FEC\_ Size},{{TI\_ NUM} - 1}}} \right)}} \\{= {\underset{j}{ma}{x\left( N_{{FEC\_ Size},j} \right)}}} \\{N_{c} = {\max \left( {N_{{FEC\_ NUM},0},{N_{{FEC\_ NUM},0}\mspace{14mu}.\;.\;.}\mspace{14mu},N_{{FEC\_ NUM},{{TI\_ NUM} - 1}}} \right)}} \\{= {\underset{j}{ma}{x\left( N_{{FEC\_ NUM},j} \right)}}}\end{matrix}$TI_NUM − 1:  Total  number  of  TI   blocks  in  a  single  frame N_(FEC_Size, j):  FEC  block  size  in  the  jth  TI  blockN_(FEC_NUM, j):  Total  number  of  FEC  blocks  in  the  jth  TI  block

FIG. 37 illustrates a time interleaving process according to anotherembodiment of the present invention.

FIG. 37 shows an embodiment of applying diagonal-type TI in a variabledata-rate system.

FIG. 37(a) illustrates a process of applying diagonal-type TI to TIblock 0 including 4 FEC blocks and FIG. 37(b) illustrates a process ofapplying diagonal-type TI to TI block 1 including 5 FEC blocks.

TI FEC blocks represent FEC blocks included in each TI block and cellvalues corresponding to the FEC blocks. TI memory indexes indicatememory indexes corresponding to cell values included in TI blocks.

The TI blocks are included in one signal frame and each FEC block mayinclude 8 cells.

The broadcast signal transmitter according to an embodiment of thepresent invention can determine a diagonal-type TI method which isequally applied to two TI blocks. Since the diagonal-type TI methodaccording to an embodiment of the present invention is determined on thebasis of a TI block including a maximum number of FEC blocks within oneframe, as described above, diagonal-type TI is determined based on TIblock 1 in the case of FIG. 37. Accordingly, the TI memory can have asize corresponding to an 8×5 (40×1) matrix.

As shown in the upper part of FIG. 37(a), the number of FEC blocksincluded in TI block 0 is 4 which is less than the number of FEC blocksincluded in TI block 1. Accordingly, the broadcast signal transmitteraccording to an embodiment of the present invention can add (pad) avirtual FEC block 23000 having a value of 0 to TI block 0 andcolumn-wise write cells corresponding to the virtual FEC block 23000into the TI memory. The position to which the virtual FEC block is addedcan be determined according to designer.

As shown in the low part of FIG. 37(a), the broadcast signal transmitteraccording to an embodiment of the present invention can diagonally readcells written in the TI memory. In this case, since the last columncorresponds to the virtual FEC block, it is possible to perform readingoperation while ignoring the cells corresponding to the virtual FECblock.

The broadcast signal transmitter according to an embodiment of thepresent invention can perform column-wise writing and diagonal readingfor TI block 1 according to the aforementioned method, as shown in FIG.37(b).

As described above, since diagonal-type TI according to an embodiment ofthe present invention is preferentially applied to a TI block includinga smaller number of FEC blocks, diagonal-type TI can be applied to TIblock 1 first in the case of FIG. 37.

FIG. 38 illustrates a process of generating TI output memory indexesaccording to another embodiment of the present invention.

FIG. 38 shows a process of generating TI output memory indexes for theabove-described two TI blocks (TI block 0 and TI block 1) and TI outputFEC blocks corresponding to TI output memory indexes.

Blocks corresponding to TI output memory indexes represent a process ofgenerating TI output memory indexes and TI output FEC blocks representcell values of FEC blocks corresponding to the generated TI outputmemory indexes.

FIG. 38(a) illustrates a process of generating TI output memory indexesof TI block 0. As shown in the upper part of FIG. 38(a), when the numberof TI memory indexes exceeds the number of cells of TI block 0, thebroadcast signal transmitter according to an embodiment of the presentinvention can ignore TI memory indexes 32 to 39 corresponding to cellsincluded in a virtual FEC block. This operation may be referred to asskip operation. Consequently, final output memory indexes for whichreading can be performed, except for the skipped TI memory indexes, aregenerated as shown in FIG. 38(a). Cell values of output FEC blockscorresponding to the final output memory indexes are shown in the lowerpart of FIG. 38(a).

FIG. 38(b) illustrates a process of generating TI output memory indexesof TI block 1. In the case of TI block 1, skip operation is not applied.The process corresponds to the aforementioned process.

The following equation represents the output memory index generationprocess for performing diagonal-type TI applicable in the aforementionedvariable data-rate system.

for  0 ≤ j ≤ TI_NUM − 1, 0 ≤ k ≤ N_(r)N_(c) − 1[Equation  13]     C_(cnt, j) = 0$\mspace{79mu} {{r_{j,k} = {{mod}\left( {k,N_{r}} \right)}},\mspace{79mu} {s_{j,k} = {{mod}\left( {r_{j,k},N_{c}} \right)}},\mspace{79mu} {c_{j,k} = {{mod}\left( {{s_{j,k} + \left\lfloor \frac{k}{N_{r}} \right\rfloor},N_{c}} \right)}}}$     θ_(j)(k) = N_(r)c_(j, k) + r_(j, k)        if  θ_(j)(k) ≤ N_(FEC_Size, j)N_(FEC_NUM, j)          π_(j)(C_(cnt, j)) = θ_(j)(k)          C_(cnt, j) = C_(cnt, j) + 1         end     endC_(cnt, j):  counter  of  actual  TI  output      memory-index  for  the  jth  TI  blockθ_(j)(k):  temporal  TI  output  memory-index  for  the  jth  TI  blockπ_(j)(k) : actual  TI  output  memory-index  for  the  jth  block

In the equation 13, the “if” statement represents the aforementionedskip operation.

FIG. 39 is a flowchart illustrating a TI memory index generation processaccording to an embodiment of the present invention.

As described above, the time interleaver according to an embodiment ofthe present invention can perform diagonal-type TI by sequentiallygenerating TI output memory indexes for sequentially input FEC blocks.

Referring to FIG. 39, the broadcast signal transmitter according to anembodiment of the present invention may set initial values (S25000).That is, the broadcast signal transmitter according to an embodiment ofthe present invention can determine a diagonal-type TI method applied toall TI blocks on the basis of a TI block including a maximum number ofFEC blocks.

Then, the broadcast signal transmitter according to an embodiment of thepresent invention may generate temporal TI memory indexes (S25100). Thatis, the broadcast signal transmitter according to an embodiment of thepresent invention can add (pad) a virtual FEC block to TI blocks havingnumbers of FEC blocks less than a predetermined TI memory index andwrite cells corresponding to TI blocks into a TI memory.

The broadcast signal transmitter according to an embodiment of thepresent invention may evaluate availability of the generated TI memoryindexes (S25200). That is, the broadcast signal transmitter according toan embodiment of the present invention can diagonally read the cellswritten in the TI memory. In this case, cells corresponding to thevirtual FEC block can be skipped and reading can be performed.

Then, broadcast signal transmitter according to an embodiment of thepresent invention may generate final TI memory indexes (S25300).

The flowchart of FIG. 39 corresponds to the process of generating TIoutput memory indexes, described with reference to FIGS. 36, 37 and 38,and may be modified according to designer.

FIG. 40 illustrates a time deinterleaving process according to anotherembodiment of the present invention.

The time deinterleaving process shown in FIG. 40 is the inverse of thetime interleaving process described with reference to FIGS. 23, 24 and25.

Particularly, time deinterleaving according to another embodiment of thepresent invention can be applied to a case in which the broadcast signalreceiver uses a single memory.

To achieve such a single-memory approach, the reading and writingoperations for the interleaved TI blocks should be accomplishedsimultaneously. The TDI procedure can be expressed as a closed-form,which leads to the efficient TDI implementation.

Time deinterleaving according to another embodiment of the presentinvention may be performed through four steps.

FIG. 40(a) illustrates the first step (step 1) of time deinterleaving.Before TDI processing for TI block 0, using TI rule, the cell valuecorresponding to a memory index ignored during TI processing is set tozero (or an identification value). That is, the blocks shown in theupper part of FIG. 40(a) represent cell values of output FEC blockscorresponding to final output memory indexes of TI block 0 and theblocks shown in the lower part of FIG. 40(a) represent cell values ofFEC blocks, which are generated by setting cell values corresponding tomemory indexes skipped in skip operation to zero.

In the second step (step 2), after step 1, output of step 1 is writtento the single-memory of size 8×5. The writing direction is identical tothe reading direction in TI processing. The broadcast signal receiveraccording to an embodiment of the present invention can perform diagonalwriting operation as the first inverse process of TI of the transmitterfor the first input TI block. That is, diagonal writing can be performedin a direction opposite to the direction of diagonal reading performedby the transmitter.

FIG. 40(b) illustrates the third step (step 3) of time deinterleaving.

Blocks corresponding to TDI FEC blocks represent cell values of inputFEC blocks. Blocks corresponding to TDI memory indexes represent TDImemory indexes corresponding to cell values of FEC blocks.

After step 2, column-wise reading operation is performed in the samedirection as the writing direction in TI processing. At this time, ifthe reading value is zero (or an identification value), it is ignored(skip operation). This skip operation corresponds to the aforementionedskip operation performed in the broadcast signal transmitter.

The following equation represents the aforementioned TDI memory indexgeneration process.

for  0 ≤ k ≤ N_(c)N_(r) − 1, 0 ≤ j ≤ TI_NUM − 1[Equation  14]     C_(cnt, j) = 0$\mspace{76mu} {{t_{j} = {{mod}\left( {{{N_{c}N_{r}} - {\left( {j + 1} \right)N_{r}} + 1},{N_{c}N_{r}}} \right)}},\mspace{76mu} {v_{j} = {t_{j\mspace{11mu}}{{mod}\left( {k,N_{r}} \right)}}},\mspace{79mu} {{\theta_{j}^{- 1}(k)} = {{mod}\left( {{{N_{r}\left\lfloor \frac{k}{N_{r}} \right\rfloor} + {{mod}\left( {v_{j},{N_{c}N_{r}}} \right)}},{N_{c}N_{r}}} \right)}},\mspace{121mu} {{{if}\mspace{14mu} {M\left( {\theta_{j}^{- 1}(k)} \right)}} \neq {0\left( {a\mspace{14mu} {value}} \right)}}}$         π_(j)⁻¹(C_(cnt, j)) = θ_(j)⁻¹(k)         C_(cnt, j) = C_(cnt, j) + 1        end    endC_(cnt, j):  counter  of  actual  TDI  output  memory-index  for  the   jth  TI  blockθ_(j)⁻¹(k) :    temporal  TDI  output  memory-index  for  the  jth  TI  blockM(θ_(j)⁻¹(k)):  the  reserved  cell  value  at  θ_(j)⁻¹(k)π_(j)⁻¹(k):  actual  TDI  output  memory-index  for  the  jth  TI  block

The “if” statement in the above equation represents the aforementionedskip operation, that is, the process of ignoring indexes when theindexes corresponding cell values stored in the TDI output memory are 0(or an arbitrary value indicating that the indexes are forciblyinserted).

FIG. 41 illustrates a time deinterleaving process according to anotherembodiment of the present invention.

As described above, the broadcast signal receiver according to anembodiment of the present invention can perform time deinterleavingusing a single memory. Accordingly, the broadcast signal receiveraccording to an embodiment of the present invention can read TI block 0and write TI block 1 simultaneously in the fourth step (step 4).

FIG. 41(a) shows TDI FEC blocks of TI block 1 written simultaneouslywith reading of TI block 0 and TDI memory indexes. The writing operationcan be performed in a direction opposite to the direction of diagonalreading performed in the broadcast signal receiver, as described above.

FIG. 41(b) shows output TDI memory indexes according to writing of TIblock 1. In this case, arrangement of the stored FEC blocks within TIblock 1 may differ from arrangement of the FEC blocks stored in the TImemory of the broadcast signal transmitter. That is, inverse processesof the writing and reading operations performed in the broadcast signaltransmitter may not be equally applied in case of a single memory.

FIG. 42 illustrates a writing method according to an embodiment of thepresent invention.

To prevent a case in which the inverse processes of the writing andreading operations performed in the broadcast signal transmitter cannotbe equally applied in case of a single memory, as described above, thepresent invention provides a method of writing FEC blocks into a TImemory in a matrix form.

The writing method illustrated in FIG. 42 can be equally applied to theaforementioned time interleaving and time deinterleaving processesaccording to an embodiment of the present invention.

FIG. 42(a) illustrates a case in which cells of FEC blocks are writtento the memory in a vector form, which corresponds to the aforementionedwriting method.

FIG. 42(b) illustrates a case in which cells of FEC blocks are writtento the memory in a matrix form. That is, the FEC blocks can be writtenin the form of an m×n matrix.

In this case, the matrix size can be changed according to designer andthe inverse processes of the writing and reading processes performed inthe broadcast signal transmitter can be equally applied to a case inwhich the broadcast signal receiver uses a single memory.

FIG. 43 is a flowchart illustrating a process of generating TDI memoryindexes according to an embodiment of the present invention.

As described above, the time deinterleaver according to an embodiment ofthe present invention can perform diagonal-type TI by sequentiallygenerating TI output memory indexes for sequentially input FEC blocks.

As shown in FIG. 43, the broadcast signal receiver according to anembodiment of the present invention may set initial values (S29000).That is, in the broadcast signal receiver according to an embodiment ofthe present invention, the cell value corresponding to a memory indexignored during TI processing is set to zero (or an identification value)using TI rue before TDI processing for the first TI block.

Subsequently, the broadcast signal receiver according to an embodimentof the present invention may generate temporal TI memory indexes(S29100). The broadcast signal receiver according to an embodiment ofthe present invention may perform diagonal writing operation as thefirst inverse process of TI of the transmitter for the first input TIblock. Then, the broadcast signal transmitter according to an embodimentof the present invention may evaluate the generated TI memory indexes(S29200). The broadcast signal transmitter according to an embodiment ofthe present invention may generate final TI memory indexes (S29300).

The flowchart shown in FIG. 43 corresponds to the process of generatingTDI output memory indexes, described with reference to FIGS. 30, 31 and32, and may be changed according to designer.

FIG. 44 is a conceptual diagram illustrating a variable data-rate systemaccording to an embodiment of the present invention.

One transmission superframe may include N_(IF_NUM) interleaving frames(IFs) and each IF may include N_(FEC_NUM) FEC blocks. In this case, thenumber of FEC blocks included in each IF may be varied. An IF accordingto an embodiment of the present invention may be defined as a block fortiming interleaving and may be referred to as the aforementioned TIblock.

The details are same as described in FIG. 36.

As described above, when the number of generated TI memory indexesexceeds the number of cells in an arbitrary IF, the broadcast signaltransmitter virtual FEC blocks can be added (zero padding) anddiagonal-type TI can be performed. Since the added virtual FEC blocksinclude cells having zero value, the broadcast signal transmitteraccording to the present invention may skip or ignore the added virtualFEC blocks. This operation may be referred to as skip operation. Theskip operation will be described in detail later.

The following equations represent the aforementioned process ofdetermining a diagonal-type TI method applied to all IFs. Specifically,the following equation represents a process of determining the sizes ofa column and a row with respect to IF including a maximum number of FECblocks in one superframe in determination of a diagonal-type TI method.

for  0 ≤ j ≤ N_(IF_NUM) − 1                      [Equation  15]$\mspace{20mu} \begin{matrix}{N_{r} = {\max \left( {N_{{FEC\_ Size},0},{N_{{FEC\_ Size},0}\mspace{14mu}.\;.\;.}\mspace{14mu},{N_{{FEC\_ Size},\text{?}} - 1}} \right)}} \\{= {\max\limits_{j}\left( N_{{FEC\_ Size},j} \right)}} \\{N_{c} = {\max \left( {N_{{FEC\_ NUM},0},{N_{{FEC\_ NUM},0}\mspace{14mu}.\;.\;.}\mspace{14mu},{N_{{FEC\_ NUM},\text{?}} - 1}} \right)}} \\{= {\max\limits_{j}\left( N_{{FEC\_ NUM},j} \right)}}\end{matrix}$N_(IF_NUM):  Total  number  of  IFs  in  a  single  super-frame N_(FEC_NUM, j):  Total  number  of  FEC  blocks  in  the  jth  IFN_(FEC_Size, j):  FEC  block  size  in  the  jth  IF, ?indicates text missing or illegible when filed

Further, an embodiment to which diagonal-type TI is applied in thevariable data-rate system described with reference to FIG. 37 can beequally applied to an IF including a plurality of FEC blocks.

The IFs are included in one super frame.

Therefore, time deinterleaving corresponding to the diagonal-type TImethod can be applied to a case in which the broadcast signal receiveruses a single memory.

In addition, the process of generating a TI output memory index,described with reference to FIG. 38, can be equally applied to an IFincluding a plurality of FEC blocks.

The following equations represent the output memory index generationprocess for performing diagonal-type TI applicable in the aforementionedvariable data-rate system.

  for  0 ≤ j ≤ N_(IF_NUM) − 1, 0 ≤ k ≤ N_(r)N_(c) − 1          [Equation  16]$\mspace{79mu} {{C_{{cnt},j} = {0\mspace{79mu} {r_{j,k} = {{mod}\left( {k,N_{r}} \right)}}}},\mspace{79mu} {t_{j,k} = {{mod}\left( {{S_{T}{zr}_{j,k}},N_{c}} \right)}},{{1 \leq S_{T} < {N_{c}\mspace{79mu} c_{j,k}}} = {{{{mod}\left( {{t_{j,k} + \left\lfloor \frac{k}{N_{r}} \right\rfloor},N_{c}} \right)}\mspace{79mu} {\theta_{j}(k)}} = {{{{N_{r}c_{j,k}} + {r_{j,k}\mspace{130mu} {{if}\mspace{14mu} {\theta_{j}(k)}}}} \leq {N_{{{FEC\_ Siz}e},j}N_{{FEC\_ NUM},j}\mspace{160mu} {\pi_{j}\left( C_{{cnt},j} \right)}}} = {{{\theta_{j}(k)}\mspace{155mu} C_{{cnt},j}} = {C_{{cnt},j} + {1\mspace{130mu} {end}\mspace{50mu} {end}S_{T}\text{:}\mspace{14mu} {diagonal}\mspace{14mu} {slope}\mspace{14mu} {for}\mspace{14mu} {use}\mspace{14mu} {in}\mspace{14mu} {interleaving}\mspace{14mu} \left( {{contant}\mspace{14mu} {value}} \right)C_{{cnt},j}\text{:}\mspace{14mu} {counter}\mspace{14mu} {of}\mspace{14mu} {actual}\mspace{14mu} {TI}\mspace{14mu} {output}\mspace{14mu} {\quad{\quad{{memory}\text{-i}{ndex}\mspace{14mu} {for}\mspace{14mu} {the}\mspace{14mu} {j{th}}\mspace{14mu} {TI}\mspace{20mu} {block}{\theta_{j}(k)}\text{:}\mspace{14mu} {temporal}\mspace{14mu} {TI}\mspace{14mu} {output}\mspace{14mu} {memory} \text{-} {index}\mspace{14mu} {f{or}}\mspace{14mu} {the}\mspace{11mu} {jth}\mspace{20mu} {TI}\mspace{14mu} {block}\text{}{\pi_{j}(k)}\text{:}\mspace{20mu} {actual}\mspace{14mu} {TI}\mspace{11mu} {{outp}{ut}}{\; \mspace{14mu}}{\quad{\quad{{memory}\text{-i}{ndex}\mspace{14mu} {for}\mspace{14mu} {the}\mspace{14mu} {j{th}}\mspace{14mu} {TI}{block}}\mspace{11mu}}}}}}}}}}}}}$

In Equation 16, the “if” statement represents the aforementioned skipoperation. In addition, Equation 16 above represents a process forgeneration of an output memory index for the aforementioned diagonaltype TI of the diagonal slope. Accordingly, a diagonal slope value isdefined as one variable. The diagonal slope according to an embodimentof the present invention can be used as a shift value which is describedabove. And the S_(T) in the above Equation can be a shift value used inthe interleaving.

In addition, the flowchart of FIG. 39 can be equally applied to an IFincluding a plurality of FEC blocks.

Furthermore, the time deinterleaving process according to anotherembodiment of the present invention, described with reference to FIGS.40 and 41, can be equally applied to the IF including a plurality of FECblocks.

The following equations represent the TDI memory index generationprocess which is applied to IF including a plurality of FEC blocks.

 for  0 ≤ k ≤ N_(c)N_(r) − 1, 0 ≤ j ≤ IF_NUM − 1          [Equation  17]$\mspace{79mu} {{C_{{cnt},j} = {0\mspace{20mu} {S_{\text{?}} = {{mod}\left( {{S_{R,{j - 1}} - S_{T}},N_{c}} \right)}}}},\; {{{where}\mspace{14mu} S_{R,0}} = {N_{c} - S_{T}}},\mspace{79mu} {r_{j,k} = {{mod}\left( {k,N_{r}} \right)}},\mspace{79mu} {t_{j,k} = {{mod}\left( {{S_{R,j}\text{?}r_{j,k}},N_{c}} \right)}},\mspace{79mu} {c_{j,k} = {{{mod}\left( {{t_{j,k} + \left\lfloor \frac{k}{N_{r}} \right\rfloor},N_{c}} \right)}\mspace{79mu} {{\theta_{j}^{- 1}(k)} = {{N_{r}c_{j,k}} + r_{j,k}}}}},\mspace{130mu} {{{{if}\mspace{14mu} {M\left( {\theta_{j}^{- 1}(k)} \right)}} \neq {0\left( {a\mspace{14mu} {value}} \right)\mspace{160mu} {\pi_{j}^{- 1}\left( C_{{cnt},j} \right)}}} = {{{\theta_{j}^{- 1}(k)}\mspace{155mu} C_{{cnt},j}} = {C_{{cnt},j} + {1\mspace{130mu} {end}\mspace{50mu} {end}C_{{cnt},j}\text{:}\mspace{14mu} {counter}\mspace{14mu} {of}\mspace{14mu} {actual}\mspace{14mu} {TDI}\mspace{14mu} {output}\mspace{14mu} {\quad{\quad{{memory}\text{-i}{ndex}\mspace{14mu} {for}\mspace{14mu} {the}{j{th}}\mspace{14mu} {IF}\mspace{20mu} {\theta_{j}^{- 1}(k)}\text{:}\mspace{14mu} {the}\mspace{14mu} {reserved}\mspace{14mu} {cell}\mspace{20mu} {value}\mspace{14mu} {at}\mspace{14mu} {\theta_{j}^{- 1}(k)}{M\left( {{\theta_{j}^{- 1}(k)}\text{:}\mspace{14mu} {temporal}\mspace{14mu} {TDI}\mspace{14mu} {output}\mspace{14mu} {memory} \text{-} {index}\mspace{14mu} {for}\mspace{14mu} {the}{jth}\mspace{14mu} {IF}\mspace{14mu} \text{}{\pi_{j}^{- 1}(k)}\text{:}{\mspace{11mu} \;}{actual}\mspace{14mu} {TDI}\mspace{14mu} {output}\mspace{14mu} {memory} \text{-} {index}\mspace{14mu} {for}\mspace{14mu} {the}\mspace{14mu} {jth}\mspace{14mu} {IF}\text{?}\text{indicates text missing or illegible when filed}} \right.}}}}}}}}}$

The “if” statement in the above equation represents the aforementionedskip operation, that is, the process of ignoring indexes when theindexes corresponding cell values stored in the TDI output memory are 0(or an arbitrary value indicating that the indexes are forciblyinserted). In addition, Equation 19 above represents a process ofgeneration of a TDI memory index for time interleaving corresponding tothe aforementioned diagonal type TI according to a diagonal slope.

The writing method according to an embodiment of the present invention,described with reference to FIG. 42, can be equally applied an IFincluding a plurality of FEC blocks.

FIG. 45 is a flowchart illustrating a process of generating TDI memoryindexes according to an embodiment of the present invention.

As described above, the time deinterleaver according to an embodiment ofthe present invention can perform diagonal-type TI by sequentiallygenerating TI output memory indexes for sequentially input FEC blocks.

As shown in FIG. 45, the broadcast signal receiver according to anembodiment of the present invention may set initial values (S30000).That is, in the broadcast signal receiver according to an embodiment ofthe present invention, the cell value corresponding to a memory indexignored during TI processing is set to zero (or an identification value)using TI rue before TDI processing for the first IF.

Then the broadcast signal receiver according to an embodiment of thepresent invention may calculate a diagonal slope to be used for TDIprocessing (S30100).

Subsequently, the broadcast signal receiver according to an embodimentof the present invention may generate temporal TI memory indexes(S30200). The broadcast signal receiver according to an embodiment ofthe present invention may perform diagonal writing operation as thefirst inverse process of TI of the transmitter for the first input IF.Then, the broadcast signal transmitter according to an embodiment of thepresent invention may evaluate the generated TI memory indexes (S30300).The broadcast signal transmitter according to an embodiment of thepresent invention may generate final TI memory indexes (S30400).

The flowchart shown in FIG. 49 corresponds to the process of generatingTDI output memory indexes, described with reference to FIGS. 27, 28 and29, and may be changed according to designer.

The below equation represents a processing of calculating an optimumshift value to provide the maximum performance in a burst channel.

$\begin{matrix}{{S_{T} = {\frac{N_{c}^{\prime} - 1}{2} + 1}}\mspace{14mu} {{for}\left\{ {\begin{matrix}{{N_{c}^{\prime} = {N_{c} + 1}},} & {{{if}\mspace{14mu} N_{c}\mspace{11mu} {mod}\mspace{11mu} 2} = 0} \\{{N_{c}^{\prime} = N_{c}},} & {{{if}\mspace{14mu} N_{c}\mspace{11mu} {mod}\mspace{11mu} 2} = 1}\end{matrix}{N_{c}:\mspace{14mu} {{column}\mspace{14mu} {size}}}} \right.}} & \left\lbrack {{Equation}\mspace{14mu} 18} \right\rbrack\end{matrix}$

When a number of IF included in a single frame is 2, the size of FECblock in two Ifs is equal to 8 and a number of FEC blocks in the firstIF is 4 and a number of FEC blocks in the second IF is 5, then themaximum value of row for TI may be 8 and the maximum number of columnfor TI may be 5. In this case, using the equation 18, the optimum shiftvalue can be 3.

FIG. 46 illustrates the concept of a variable bit-rate system accordingto an embodiment of the present invention.

The variable bit-rate system according to an embodiment of the presentinvention is another embodiment of the aforementioned variable data-ratesystem.

Specifically, a transport superframe, shown in FIG. 46, is composed ofN_(TI_NUM) TI groups and each TI group can include N_(BLOCK_TI) FECblocks.

In this case, TI groups may respectively include different numbers ofFEC blocks. The TI group according to an embodiment of the presentinvention can be defined as a block for performing time interleaving andcan be used in the same meaning as the aforementioned TI block or IFThat is, one IF can include at least one TI block and the number of FECblocks in the TI block is variable.

Details are as described with reference to FIGS. 36 and 44.

When TI groups include different numbers of FEC blocks, the presentinvention performs interleaving on the TI groups using one twistedrow-column block interleaving rule in an embodiment. Accordingly, thereceiver can perform deinterleaving using a single memory.

A description will be given of an input FEC block memory arrangementmethod and reading operation of the time interleaver in consideration ofvariable bit-rate (VBR) transmission in which the number of FEC blockscan be changed per TI group.

FIG. 47 illustrates writing and reading operations of block interleavingaccording to an embodiment of the present invention.

FIG. 47 corresponds to another embodiment of the operation shown in FIG.26 and thus detailed description thereof is omitted.

FIG. 48 shows equations representing block interleaving according to anembodiment of the present invention.

The equations shown in the figure represent block interleaving appliedper TI group. As expressed by the equations, shift values can berespectively calculated in a case in which the number of FEC blocksincluded in a TI group is an odd number and a case in which the numberof FEC blocks included in a TI group is an even number. That is, blockinterleaving according to an embodiment of the present invention cancalculate a shift value after making the number of FEC blocks be anodd-number.

A time interleaver according to an embodiment of the present inventioncan determine parameters related to interleaving on the basis of a TIgroup having a maximum number of FEC blocks in the correspondingsuperframe. Accordingly, the receiver can perform deinterleaving using asingle memory.

Here, for a TI group having a smaller number of FEC blocks than themaximum number of FEC blocks, virtual FEC blocks corresponding to adifference between the number of FEC blocks and the maximum number ofFEC blocks can be added.

Virtual FEC blocks according to an embodiment of the present inventioncan be inserted before actual FEC blocks. Subsequently, the timeinterleaver according to an embodiment of the present invention canperform interleaving on the TI groups using one twisted row-column blockinterleaving rule in consideration of the virtual FEC blocks. Inaddition, the time interleaver according to an embodiment of the presentinvention can perform the aforementioned skip operation when amemory-index corresponding to virtual FEC blocks is generated duringreading operation. In the following writing operation, the number of FECblocks of input TI groups is matched to the number of FEC blocks ofoutput TI groups. Consequently, according to time interleaving accordingto an embodiment of the present invention, loss of data rate of dataactually transmitted may be prevented through skip operation even ifvirtual FEC blocks are inserted in order to perform efficientsingle-memory deinterleaving in the receiver.

FIG. 49 illustrates virtual FEC blocks according to an embodiment of thepresent invention.

The left side of the figure shows parameters indicating a maximum numberof FEC blocks in a TI group, the actual number of FEC blocks included ina TI group and a difference between the maximum number of FEC blocks andthe actual number of FEC blocks, and equations for deriving the numberof virtual FEC blocks.

The right side of the figure shows an embodiment of inserting virtualFEC blocks into a TI group. In this case, the virtual FEC blocks can beinserted before actual FEC blocks, as described above.

FIG. 50 shows equations representing reading operation after insertionof virtual FEC blocks according to an embodiment of the presentinvention.

Skip operation illustrated in the figure can skip virtual FEC blocks inreading operation.

FIG. 51 is a flowchart illustrating a time interleaving processaccording to an embodiment of the present invention.

A time interleaver according to an embodiment of the present inventioncan setup initial values (S67000).

Then, the time interleaver according to an embodiment of the presentinvention can perform writing operation on actual FEC blocks inconsideration of virtual FEC blocks (S67100).

The time interleaver according to an embodiment of the present inventioncan generate a temporal TI address (S67200).

Subsequently, the time interleaver according to an embodiment of thepresent invention can evaluate the availability of the generated TIreading address (S67300). Then, the time interleaver according to anembodiment of the present invention can generate a final TI readingaddress (S67400).

The time interleaver according to an embodiment of the present inventioncan read the actual FEC blocks (S67500).

FIG. 52 shows equations representing a process of determining a shiftvalue and a maximum TI block size according to an embodiment of thepresent invention.

The figure shows an embodiment in which the number of TI groups is 2,the number of cells in a TI group is 30, the number of FEC blocksincluded in the first TI group is 5 and the number of FEC blocksincluded in the second TI block is 6. While a maximum number of FECblocks is 6, 6 is an even number. Accordingly, a maximum number of FECblocks, which is adjusted in order to obtain the shift value, can be 7and the shift value can be calculated as 4.

FIGS. 53, 54 and 55 illustrate a TI process of the embodiment shown inFIG. 52.

FIG. 53 illustrates writing operation according to an embodiment of thepresent invention.

FIG. 53 shows writing operation for the two TI groups described withreference to FIG. 52.

A block shown in the left side of the figure represents a TI memoryaddress array and blocks shown in the right side of the figureillustrate writing operation when two virtual FEC blocks and one virtualFEC block are respectively inserted into two continuous TI groups. Sincethe adjusted maximum number of FEC blocks is 7, as described above, twovirtual FEC blocks are inserted into the first TI group and one virtualFEC block is inserted into the second TI group.

FIG. 54 illustrates reading operation according to an embodiment of thepresent invention.

A block shown in the left side of the figure represents a TI memoryaddress array and blocks shown in the right side of the figureillustrate reading operation when two virtual FEC blocks and one virtualFEC block are respectively inserted into two continuous TI groups. Inthis case, reading operation can be performed on the virtual FEC blocksin the same manner as the reading operation performed on actual FECblocks.

FIG. 55 illustrates a result of skip operation in reading operationaccording to an embodiment of the present invention.

As shown in the figure, virtual FEC blocks can be skipped in two TIgroups.

FIGS. 56 and 57 illustrate time deinterleaving corresponding to areverse of TI described with reference to FIGS. 52 to 55. Specifically,FIG. 56 illustrates time deinterleaving for the first TI group and FIG.57 illustrates time deinterleaving for the second TI group.

FIG. 56 shows a writing process of time deinterleaving according to anembodiment of the present invention.

In this case, the parameters described with reference to FIG. 52 can beequally applied.

A left block in the figure shows a TI memory address array, a middleblock shows the first TI group input to a time deinterleaver and a rightblock shows a writing process performed in consideration of virtual FECblocks that are skipped with respect to the first TI group.

As shown in the figure, two virtual FEC blocks skipped during TI can berestored for correct reading operation in the writing process. In thiscase, the positions and quantity of the skipped two virtual FEC blockscan be estimated through an arbitrary algorithm.

FIG. 57 illustrates a writing process of time deinterleaving accordingto another embodiment of the present invention.

A left block in the figure shows a TI memory address array, a middleblock shows the second TI group input to the time deinterleaver and aright block shows a writing process performed in consideration ofvirtual FEC blocks that are skipped with respect to the second TI group.

As shown in the figure, one virtual FEC block skipped during TI can berestored for correct reading operation in the writing process. In thiscase, the position and quantity of the skipped one virtual FEC block canbe estimated through an arbitrary algorithm.

FIG. 58 shows equations representing reading operation of timedeinterleaving according to another embodiment of the present invention.

A TDI shift value used in the receiver can be determined by a shiftvalue used in the transmitter, and skip operation can skip virtual FECblocks in reading operation, similarly to skip operation performed inthe transmitter.

FIG. 59 is a flowchart illustrating a time deinterleaving processaccording to an embodiment of the present invention.

A time deinterleaver according to an embodiment of the present inventioncan setup initial values (S75000).

Then, the time deinterleaver according to an embodiment of the presentinvention can perform writing operation on actual FEC blocks inconsideration of virtual FEC blocks (S75100).

Subsequently, the time deinterleaver according to an embodiment of thepresent invention can generate a temporal TDI reading address (S75200).

The time deinterleaver according to an embodiment of the presentinvention can evaluate the availability of the generated TDI readingaddress (S75300). Then, the time deinterleaver according to anembodiment of the present invention can generate a final TDI readingaddress (S75400).

Subsequently, the time deinterleaver according to an embodiment of thepresent invention can read the actual FEC blocks (S75500).

FIG. 60 is a block diagram of a time interleaver according to anotherembodiment of the present invention.

Specifically, the time interleaver according to an embodiment of thepresent invention may include a twisted block interleaver and aconvolutional interleaver.

The time interleaver according to an embodiment of the present inventionmay perform a block interleaving (or twisted block interleaving)operation, and then perform a convolutional interleaving operation.

In addition, the time interleaver according to an embodiment of thepresent invention is applicable not only to a constant bit rate (CBR)system having a constant number of FEC blocks in an interleaving frame(IF) but also to a variable bit rate (VBR) system having a variablenumber of FEC blocks in an IF. The VBR system according to an embodimentof the present invention may be used in the same meaning as theabove-described variable data rate (VDR) system.

Specifically, the time interleaver or the twisted block interleaveraccording to an embodiment of the present invention may operate based onIFs. In this case, each IF may be divided into interleaving units (IUs)and input to the convolutional interleaver. As described above, an IFmay be used in the same concept as a TI block. That is, one IF mayinclude one or more TI blocks, and the number of FEC blocks included inthe TI block is variable.

A description is now given of a CBR system having a FEC block size of 30and an IU size of 3, as an embodiment of operation of the timeinterleaver.

FIGS. 61 to 63 are views illustrating a twisted block interleavingoperation and a convolutional interleaving operation according to anembodiment of the present invention.

Specifically, FIG. 61 is a view illustrating a twisted blockinterleaving operation. As described above, the interleaving operationaccording to an embodiment of the present invention may be performedbased on IFs. The left part of the figure illustrates a diagonal-wisereading process applied to each IF. The right part of the figureillustrates a diagonal-wise writing process applied to output IFs of thetwisted block interleaver according to an embodiment of the presentinvention. A twisted block interleaving operation applied to each IF isthe same as that described above, and thus a detailed descriptionthereof is omitted here.

FIGS. 62 and 63 are views illustrating a convolutional interleavingoperation.

Specifically, FIG. 62 illustrates a convolutional interleavingoperation, and FIG. 63 illustrates output frames based on a readingoperation of a convolutional interleaver. The convolutional interleavingoperation illustrated in these figures may be performed based on IFs,and the reading operation of the convolutional interleaver may beperformed based on frames. A detailed description of these operations isthe same as that given above.

FIG. 64 is a block diagram of a time deinterleaver according to anembodiment of the present invention.

Specifically, the time deinterleaver according to an embodiment of thepresent invention may perform a process inversely corresponding to theprocess performed by the time interleaver according to an embodiment ofthe present invention, which is described above in relation to FIGS. 60to 63. The time deinterleaver according to an embodiment of the presentinvention may include a convolutional deinterleaver and a twisted blockdeinterleaver. Accordingly, the time deinterleaver according to anembodiment of the present invention may perform convolutionaldeinterleaving on input data, and then perform twisted blockdeinterleaving.

FIG. 65 is a view illustrating memory configurations of a timeinterleaver and a time deinterleaver.

The left part of the figure illustrates memory configuration of the timeinterleaver of the transmitter, and the right part of the figureillustrates memory configuration of the time deinterleaver of thereceiver.

The memory configuration of the time deinterleaver of the receiver maybe designed inversely from the memory configuration of the timeinterleaver of the transmitter. Specifically, the memory configurationof the time deinterleaver of the receiver may be designed inconsideration of the convolutional interleaving operation of thetransmitter which is illustrated in FIG. 62.

FIG. 66 is a view illustrating a time deinterleaving operation accordingto an embodiment of the present invention.

Specifically, FIG. 66 illustrates a time deinterleaving operationinversely corresponding to the time interleaving operation describedabove in relation to FIGS. 60 to 63. Accordingly, the time deinterleaveraccording to an embodiment of the present invention may performconvolutional deinterleaving on a plurality of signal frames including aplurality of TI blocks (or IF blocks) which are spread over the signalframes through time interleaving of the transmitter, and then performtwisted block deinterleaving to output complete IFs.

FIG. 67 is a view illustrating the structure of a time interleaveraccording to an embodiment of the present invention.

The time interleaver according to an embodiment of the present inventionmay be called a hybrid time interleaver, and may include theabove-described twisted block interleaver and the convolutionalinterleaver.

As illustrated in FIG. 67, the time interleaver according to anembodiment of the present invention may perform intra frame interleavingand inter frame interleaving. Specifically, the above-described twistedblock interleaver may perform intra frame interleaving, and theabove-described convolutional interleaver may perform inter frameinterleaving.

Intra frame interleaving according to an embodiment of the presentinvention refers to interleaving performed only within one signal frameor one TI block (IF, TI group), and inter frame interleaving accordingto an embodiment of the present invention refers to interleaving betweensignal frames or interleaving between TI blocks. Although intra frameinterleaving can be performed by only the twisted block interleaver,inter frame interleaving may be performed by both of the twisted blockinterleaver and the convolutional interleaver. This is variabledepending on a designer's intention.

Operations of the twisted block interleaver and the convolutionalinterleaver are the same as those described above, and thus a detaileddescription thereof is omitted here.

FIG. 68 is a view illustrating a reading operation performed afterconvolutional interleaving.

Specifically, FIG. 68 illustrates a reading operation of theconvolutional interleaver and output of the reading operation. Adescription is now given of a detailed reading operation of a CBR systemhaving a FEC block size of 30 and an IU size of 3. A reading operationof the convolutional interleaver according to an embodiment of thepresent invention may be performed based on IFs. That is, as illustratedin the figure, the convolutional interleaver according to an embodimentof the present invention may sequentially read IFs included in the sameframe in a row-wise manner among IFs spread over a plurality of signalframes.

FIG. 69 is a view illustrating the structure of a time deinterleaveraccording to an embodiment of the present invention.

The time deinterleaver according to an embodiment of the presentinvention may perform a process inversely corresponding to the processperformed by the hybrid time interleaver, which is described above.Accordingly, the time deinterleaver according to an embodiment of thepresent invention may be called a hybrid time deinterleaver, and mayinclude the above-described convolutional deinterleaver and the twistedblock deinterleaver.

As illustrated in FIG. 69, the hybrid time deinterleaver according to anembodiment of the present invention may perform inter framedeinterleaving and intra frame deinterleaving. Specifically, theabove-described convolutional deinterleaver may perform inter framedeinterleaving, and the twisted block deinterleaver may perform intraframe deinterleaving.

FIGS. 70 and 71 are views illustrating a time deinterleaving operationaccording to an embodiment of the present invention.

FIG. 70 is a view illustrating a convolutional deinterleaving operationaccording to an embodiment of the present invention.

The convolutional deinterleaving operation illustrated in FIG. 70 mayinversely correspond to the convolutional interleaving operationdescribed above in relation to FIG. 62. Specifically, FIG. 70 is a viewillustrating a detailed operation of a time deinterleaver having thememory configuration of the time deinterleaver described above inrelation to FIG. 65. The left part of FIG. 70 is a view illustrating IFsinputs to the time deinterleaver.

The convolutional deinterleaving operation of FIG. 70 according to anembodiment of the present invention is performed between signal frames.Accordingly, the convolutional deinterleaver according to an embodimentof the present invention may perform convolutional deinterleaving on aplurality of input signal frames to output complete IFs.

FIG. 71 is a view illustrating a twisted deinterleaving operationaccording to an embodiment of the present invention.

The twisted deinterleaving operation illustrated in FIG. 71 mayinversely correspond to the twisted interleaving operation describedabove in relation to FIG. 61. The left part of FIG. 71 illustratesoutput IFs of the convolutional deinterleaver. The right part of FIG. 71illustrates output IFs of the twisted block deinterleaver. Specifically,the twisted block deinterleaver according to an embodiment of thepresent invention may sequentially perform a diagonal-wise readingprocess and a diagonal-wise writing process. As a result, the twistedblock deinterleaver may output IFs equal to the input IFs illustrated inFIG. 48.

FIG. 72 is a flowchart illustrating a method for transmitting broadcastsignals according to an embodiment of the present invention.

The apparatus for transmitting broadcast signals according to anembodiment of the present invention or the BICM block in the apparatusfor transmitting broadcast signals or the FEC encoder can encode servicedata corresponding to a number of physical paths (S72000). As describedabove, a physical path is a logical channel in the physical layer thatcarries service data or related metadata, which may carry one ormultiple service(s) or service component(s) and the title can be changedaccording to designer's intention. The physical path according to anembodiment of the present invention is equal to the DP which isdescribed above. The detailed process of encoding is as described inFIG. 1 to FIG. 29.

The apparatus for transmitting broadcast signals according to anembodiment of the present invention or the BICM block in the apparatusfor transmitting broadcast signals or the time interleaver can timeinterleave the encoded service data in each physical path (S72100). Theapparatus for transmitting broadcast signals according to an embodimentof the present invention or the BICM block or the time interleaver canperform a twisted block interleaving the encoded service data by a TI(Time interleaving) block and a convolutional interleaving the twistedblock interleaved service data. The detailed process of this step is asdescribed in FIG. 25 to FIG. 71.

Then, the apparatus for transmitting broadcast signals according to anembodiment of the present invention or the frame building block canbuild at least one signal frame including the time interleaved servicedata (S72200). The detailed process of this step is as described in FIG.1 to FIG. 29.

Subsequently, the apparatus for transmitting broadcast signals accordingto an embodiment of the present invention or the OFDM generator block inthe apparatus for transmitting broadcast signals can modulate data inthe built at least one signal frame by an OFDM (Orthogonal FrequencyDivision Multiplex) scheme (S72300) and the apparatus for transmittingbroadcast signals according to an embodiment of the present invention orthe OFDM generator block or transmitter can transmit broadcast signalshaving the modulated data (S72400). The detailed process of this step isas described in FIG. 1 to FIG. 29.

It will be appreciated by those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the spirit or scope of the inventions. Thus, itis intended that the present invention covers the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

Both apparatus and method inventions are mentioned in this specificationand descriptions of both of the apparatus and method inventions may becomplementarily applicable to each other.

A module, a unit or a block according to embodiments of the presentinvention is a processor/hardware executing a sequence of instructionsstored in a memory (or storage unit). The steps or the methods in theabove described embodiments can be operated in/by hardwares/processors.In addition, the method of the present invention may be implemented as acode that may be written on a processor readable recording medium andthus, read by the processors provided in the apparatus according toembodiments of the present invention.

1-10. (canceled)
 11. An apparatus for receiving broadcast signals, theapparatus comprising: a tuner to receive the broadcast signals carryingat least one signal frame; a demodulator to demodulate the broadcastsignals by an Orthogonal Frequency Division Multiplex (OFDM) scheme; atime deinterleaver to de-interleave data in the at least one signalframe based on a convolutional de-interleaver and a blockde-interleaver, the convolutional de-interleaver to de-interleave thedata in the at least one signal frame, the block de-interleaver to writethe convolutional de-interleaved data to a memory based on a TimeInterleaving (TI) block including a number of actual Forward ErrorCorrection (FEC) blocks having the convolutional de-interleaved data,and to read the TI block from the memory; and a decoder to decode thetime-de-interleaved data.
 12. A method of receiving broadcast signals,the apparatus comprising: receiving the broadcast signals carrying atleast one signal frame; demodulating the broadcast signals by anOrthogonal Frequency Division Multiplex (OFDM) scheme; timede-interleaving data in the at least one signal frame based on aconvolutional de-interleaving and a block de-interleaving, theconvolutional de-interleaving de-interleaving the data in the at leastone signal frame, the block de-interleaving writing the convolutionalde-interleaved data to a memory based on a Time Interleaving (TI) blockincluding a number of actual Forward Error Correction (FEC) blockshaving the convolutional de-interleaved data, and reading the TI blockfrom the memory; and decoding the time-de-interleaved data.